Automatic hubs 1991 Bronco

[carpenter53]

I have recently got back into a Bronco.Had a 1978 years ago and like a fool traded it. Just bought a 1991 Eddie Bauer and am enjoying it BUT I have an issue. Evey so often ( 3 times in 4 months) it will lock up in gear. I do not know if it is the transmission - transfer case - or maybe even the front hubs.When it does it it won't go at all, not even in neutral.Each time I have let it sit while making plans to haul it to get it fixed. then when I get ready to load it or drive it there it runs and shifts perfect. I have noticed that when cold it takes a long while to shift into OD.I would welcome any advice or hints on what to do .

 

[miesk5]

yo Carpenter,

WELCOME!

Try this Operational Test;

Remember to block the wheels.

This would work for testing manual hubs too, just lock them 1st;

"...Place transfercase in 2HI or Neutrall.

2. Lying under vehicle, turn front drive shaft (one direction only).

3. Automatic hubs should lock after 1 to 5 turns of driveshaft (one direction only). After step 3 the hubs should lock, youll know they are locked becouse you will hear a click from both hubs and you will no longer be able to turn the front drive shaft (in the same direction). If this is not the case then continue to step 4. If you can no longer turn the drive shaft (in the same direction) then skip to step 7.

4. If you can still turn the drive shaft (one direction only) then one or more of your Auto hubs is not working.

5. Continuing to turn the Drive shaft (one direction only).

6. Look at the u-joints for the front stub axles, if both are turning then both front hubs are malfunctioning, if only one is turning then the one that is not turning is locked and the one turning is malfuctioning. Replace as necosary (preferably with manual hubs, Auto hubs have Yams in them)

7. To unlock the hubs, turn drive shaft in opposite direction until you hear a click from the hubs.

To check for transfer case engagement.

1. Place pushbutton transfercase in either 4 HI or 4LO.

2. lie under vehicle.

3. You should not be able to turn front drive-shaft in either direction.

4. If you can turn the front drive shaft then your transfer case is not shifting properly..."

Source: by Gacknar

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Do you have the AOD or E4OD trans?

E4OD, AOD & C6 Pan Identification & Driver Side pics by Kenneth. Shift Indicator Patterns & Indicator pics (AOD, C6 & E4OD); AOD have 14 pan bolts, P-R-N-(D)-D-1 shifter pattern, note, OD is actually a (D) - pic by trigger; C6 have 17 pan bolts, P-R-N-D-2-1, shifter indicator pattern - pic by miesk5; E4OD have 20 pan bolts; P-R-N-D-2-1 shifter shifter indicator pattern - pic by Chris A.

Source: by miesk5 at Ford Bronco Zone Forums http://broncozone.com/topic/22732-1990-bronco-351/

Four Wheel Drive (4X4) General Information, Operation & Troubleshooting TSB 92-1-8 for Bronco, F Series & Ranger (COMPLETE); Includes Electric Shift On The Fly (ESOF) Troubleshooting & Hub Operation; same for 87-96Source: by Ford via Chilton http://content.chiltonsonline.com/TSB/displayTSBHandler.ashx?assetID=36059&key=6kAUBD5BruOJf%2f3tgozUqjXM3RdbjcQqW4sVWiE%2fp2IojfpfKqM07dr61%2bQAWHtTZr4ceHaQGlj8NylACcNZ4qedMqy4JdYyAXN5akgfkpHUz4aCpJyaaA%3d%3d

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Is Check Engine Light (CEL) on all the time?

Check Engine Light (CEL) comes on when the electronic engine control system is not working properly. The check engine warning indicator comes on briefly when the ignition switch lock cylinder is turned to ON, and should turn off when the engine starts. If the check engine warning indicator does not come on when the ignition switch lock cylinder is turned to ON or if it comes on while the vehicle is moving, the system is malfunctioning

If the CEL does not light up at all when starting it; then suspect that someone removed it.

If you have not heard any unusual sounds from transfer case or vibes then we can iggie it and try to troubleshoot the trans or a sensor by checking for codes;

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

http://broncozone.com/topic/14269-code-reader/page__pid__74587__mode__threaded

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.

Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.

Look Codes up in my broncolinks.com site using the new Search function.

And Post em here according to:

KOEO

&

KOER

 

[carpenter53]

yo Carpenter,

WELCOME!

Try this Operational Test;

Remember to block the wheels.

This would work for testing manual hubs too, just lock them 1st;

"...Place transfercase in 2HI or Neutrall.

2. Lying under vehicle, turn front drive shaft (one direction only).

3. Automatic hubs should lock after 1 to 5 turns of driveshaft (one direction only). After step 3 the hubs should lock, youll know they are locked becouse you will hear a click from both hubs and you will no longer be able to turn the front drive shaft (in the same direction). If this is not the case then continue to step 4. If you can no longer turn the drive shaft (in the same direction) then skip to step 7.

4. If you can still turn the drive shaft (one direction only) then one or more of your Auto hubs is not working.

5. Continuing to turn the Drive shaft (one direction only).

6. Look at the u-joints for the front stub axles, if both are turning then both front hubs are malfunctioning, if only one is turning then the one that is not turning is locked and the one turning is malfuctioning. Replace as necosary (preferably with manual hubs, Auto hubs have Yams in them)

7. To unlock the hubs, turn drive shaft in opposite direction until you hear a click from the hubs.

To check for transfer case engagement.

1. Place pushbutton transfercase in either 4 HI or 4LO.

2. lie under vehicle.

3. You should not be able to turn front drive-shaft in either direction.

4. If you can turn the front drive shaft then your transfer case is not shifting properly..."

Source: by Gacknar

--

Do you have the AOD or E4OD trans?

E4OD, AOD & C6 Pan Identification & Driver Side pics by Kenneth. Shift Indicator Patterns & Indicator pics (AOD, C6 & E4OD); AOD have 14 pan bolts, P-R-N-(D)-D-1 shifter pattern, note, OD is actually a (D) - pic by trigger; C6 have 17 pan bolts, P-R-N-D-2-1, shifter indicator pattern - pic by miesk5; E4OD have 20 pan bolts; P-R-N-D-2-1 shifter shifter indicator pattern - pic by Chris A.

Source: by miesk5 at Ford Bronco Zone Forums http://broncozone.com/topic/22732-1990-bronco-351/

Four Wheel Drive (4X4) General Information, Operation & Troubleshooting TSB 92-1-8 for Bronco, F Series & Ranger (COMPLETE); Includes Electric Shift On The Fly (ESOF) Troubleshooting & Hub Operation; same for 87-96Source: by Ford via Chilton http://content.chiltonsonline.com/TSB/displayTSBHandler.ashx?assetID=36059&key=6kAUBD5BruOJf%2f3tgozUqjXM3RdbjcQqW4sVWiE%2fp2IojfpfKqM07dr61%2bQAWHtTZr4ceHaQGlj8NylACcNZ4qedMqy4JdYyAXN5akgfkpHUz4aCpJyaaA%3d%3d

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Is Check Engine Light (CEL) on all the time?

Check Engine Light (CEL) comes on when the electronic engine control system is not working properly. The check engine warning indicator comes on briefly when the ignition switch lock cylinder is turned to ON, and should turn off when the engine starts. If the check engine warning indicator does not come on when the ignition switch lock cylinder is turned to ON or if it comes on while the vehicle is moving, the system is malfunctioning

If the CEL does not light up at all when starting it; then suspect that someone removed it.

If you have not heard any unusual sounds from transfer case or vibes then we can iggie it and try to troubleshoot the trans or a sensor by checking for codes;

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

http://broncozone.com/topic/14269-code-reader/page__pid__74587__mode__threaded

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.

Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.

Look Codes up in my broncolinks.com site using the new Search function.

And Post em here according to:

KOEO

&

KOER

 

[carpenter53]

Thanks so much for the response and the info. I have done the first test. when I turned the drive-shaft I heard the hubs click and the shaft stopped turning.That means the hubs locked in. Got that. But, when I tried to un-lock the hubs the shaft would not turn either direction.Does this mean the hubs are not un-locking properly and if so could this be the root of my problem. Could the hubs be bound up and not let the vehicle pull itself or even roll in neutral, and then in time release and become free.

In the test of the transfer case , should the motor be running or not?

I do have the E4OD transmission. Is this issue one that is typical of the E4OD? Or am I on the right track to finding my problem? Have not heard any unusual noise from underneath And the check engine light is not on all the time , not blinking at all. It does cycle when I turn the key on .

Thanks again for helping me.

 

[miesk5]

yo C,

Anything that is damaged inside the hubs or binds the internals can prevent it from unlocking. The most noticeable symptoms are popping or banging noise & extreme shuddering from hubs and up to steering wheel while driving on dry roads and/or increased front tire wear. You may have what Ford describes as just driveline windup; see this in the Ford TSB I posted above

Another test involves placing the Bronco on a lift and starting and placing in 4X4

Operational Test in a 96; "...Automatic Locking Hubs: Raise vehicle on a hoist so that all wheels are off the ground. Start engine (6007) with vehicle in neutral and transfer case in two-wheel drive. Front wheels should spin freely by hand. Put transfer case in 4WD and put vehicle in gear. Front and rear wheels should rotate together. Put vehicle in neutral and spin front wheels by hand in the forward direction. The front axle and front driveshaft should rotate with the wheels. The additional load of the drivetrain components should be felt once the hub has been engaged. To disengage the hubs, spin the wheels in the opposite direction until an audible click is heard. Spin wheels forward again and they should rotate freely without the axle and driveshaft rotating. Repeat the procedure, only shift into 4-wheel drive and put the vehicle in reverse. This time the hubs should release when the front wheels are spun in the forward direction. NOTE: While the vehicle is hoisted, shift into 4-wheel drive from a dead stop and not while rear wheels are rotating in order to avoid slamming the hub locks into the lock position. Road Test; When checking front hubs for proper operation, road test the vehicle to make sure the hubs will remain engaged while under load. This is accomplished by engaging 4-wheel drive and taking the vehicle through several turns (both forward and backward) on dry pavement. This will put an additional load on the front wheel at the outside of the turn because it is traveling the greatest distance. Driving through several turns while traveling in different directions will make sure that both sides of the hub teeth have been tested under load. Hubs that are not sufficiently engaged will pop out when loaded. This is due to the driveline releasing windup and is an indication of hub malfunction. If slippage is suspected, mark the tire and axle shaft with chalk (after locking the hub) and apply a heavy torque load several times. Then inspect your original indexing marks. If they are no longer aligned, the hubs are not remaining locked when under load. They will have to be replaced. Should hublocks become submerged in water or mud for a long period of time, water may get past the seals and into the hubs and axle. In this case, all water must be expelled from the system

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Try that Test for Codes by BroncoJoe anyway.

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Manual Lever Position (MLPS) Nagging Neutral Nonsense & Pinpoint Test; btw, Ford oftens refers to the MLPS as Transmission Range (TR) Sensor

The transmission range (TR) sensor is transmission-mounted on driver's side of transmission

The powertrain control module (PCM) (12A650) monitors the voltage across a series of step-down resistors that correspond to the position of the manual control lever (7A256). The PCM uses this information in determining desired gear and EPC pressure.

The TR sensor permits the engine to start only in the PARK and NEUTRAL positions and activates the backup lamps in the REVERSE position. The sensor also contains neutral sense circuitry for 4x4 applications.

Check connector for; tight seating and corrosion, damage, wire strands damaged,..

by Pete L at http://www.transonline.com/transdigest/magazines/1998-10/Shift%20Pointers/index.html

Excerpts;

"...One of the most-difficult problems to diagnose on a Ford car or truck is a sudden neutral condition while the vehicle is cruising in 4th gear. Now this can have a number of causes, depending on which transmission is in the car or truck, but the cause we are going to discuss here is that #(~! *&A% Manual Lever Position Sensor – that’s right, the old MLPS. This sensor is responsible for more malfunctions than any other sensor in the system, and the kicker is that it seldom stores a code 67 or 634. Actually there is a standing joke in our industry that says, “You got a problem with a Ford, change the MLPS; it fixes everything,” which ain’t that funny because it’s not that far from the truth. Some of the problems the MLPS can cause are wrong gear starts, TCC hunting, no 4th gear, engine stalling, high or erratic line pressure and the problem that this article is about – a sudden neutral condition. Whether the MLPS is attached to an E4OD, AXODE, AODE or CD4E, the operating characteristics are the same. What that means is the MLPS is classified as a step-down resistor. The MLPS is supplied 5 volts from the computer as a reference voltage, and as the shift lever is moved from park toward manual low, the voltage in each gear-shift position will decrease as shown in Figure 1. The MLPS also can be checked for correct resistance, also shown in Figure 1. This way, if the resistance checked good on the bench but the voltage does not check good in the vehicle, you know there must be a wiring or ground problem. I know what you are thinking: You replace the MLPS on every job you do, so why should you check the resistance on a new part? Well, that’s fine, but one thing has become very clear lately: NEW DOES NOT MEAN GOOD! Now, let’s get to the meat of the problem..." READ MORE

Manual Lever Position Sensor (MLPS) Connector C1012 Pin-Out Diagram

Source: by Ryan M (FireGuy50) at http://oldfuelinjection.com/files/Trans_harness.gif

 

[carpenter53]

The holidays are over and I am finally able to get back on trying to diagnose the problem with my 91 Bronco.

I had originally asked about my bronco locking up in gear or binding up and not able to pull at all.

It feels like on all four wheels the brakes are locked up.

As miesk5 told me to do, I ck-ed the transfer case for operation. It was. I ck-ed the hubs andthey were locking in, but when I went to un-lock them the driveshaft would not turn at all.

I then pulled the codes and none of them were connected to the transmission or transfer case.

The codes were: KOEO = 32/34/35/67 & KOER = 12/21//22/65/32/77

At that time Isuspected the hubs were locking up,So I pulled the front driveshaft and marked the yoke. Drove it for a few days an dthe yoke never moved. But = it still did it's thing and locked-up or whatever it is doing.

Then about three days later I driving it and stopped at a store, put in park and waited. Later I started it, put in drive and the transfer case had developed a knock. Towed it home and ck-ed fluid level and smell, both were fine. It will knock w/engine running and in park but is louder in gear. Have not put into 4 HI or 4 LO Had fear of doing more damage.

I am at a loss at what to do. I am ready to swap-out or repair whatever is wrong. (transmission / transfer case / hubs / brakes / or whatever)

I need some help.

THANKS

 

[miesk5]

yo C,

For now;

And you can search fr each DTC using the internal Search feature;

Start with; DTC

then a space

then add the number

STARTING WITH 67 because that could be the issue;

E4OD Manual Lever Position (MLPS); No Upshifts, 4th Gear Starts, Harsh Upshifts, Neutrals Out After Shifts

DTC 67 & DTC 634; Manual Lever Position (MLPS) Nagging Neutral Nonsense & Pinpoint Test; "...One of the most-difficult problems to diagnose on a Ford car or truck is a sudden neutral condition while the vehicle is cruising in 4th gear. Now this can have a number of causes, depending on which transmission is in the car or truck, but the cause we are going to discuss here is that #(~! *&A% Manual Lever Position Sensor – that’s right, the old MLPS. This sensor is responsible for more malfunctions than any other sensor in the system, and the kicker is that it seldom stores a code 67 or 634. Actually there is a standing joke in our industry that says, “You got a problem with a Ford, change the MLPS; it fixes everything,” which ain’t that funny because it’s not that far from the truth. Some of the problems the MLPS can cause are wrong gear starts, TCC hunting, no 4th gear, engine stalling, high or erratic line pressure and the problem that this article is about – a sudden neutral condition. Whether the MLPS is attached to an E4OD, AXODE, AODE or CD4E, the operating characteristics are the same. What that means is the MLPS is classified as a step-down resistor. The MLPS is supplied 5 volts from the computer as a reference voltage, and as the shift lever is moved from park toward manual low, the voltage in each gear-shift position will decrease as shown in Figure 1. The MLPS also can be checked for correct resistance, also shown in Figure 1. This way, if the resistance checked good on the bench but the voltage does not check good in the vehicle, you know there must be a wiring or ground problem. I know what you are thinking: You replace the MLPS on every job you do, so why should you check the resistance on a new part? Well, that’s fine, but one thing has become very clear lately: NEW DOES NOT MEAN GOOD! Now, let’s get to the meat of the problem. As you can see in Figure 1, the voltage in the drive/overdrive position can be 1.88 to 2.30 volts. The O.D. Cancel button, on those vehicles equipped with one, has no effect on the voltage seen in the drive position, nor does it matter whether the vehicle has a gas or diesel engine. This would be the voltage seen in the D or D position if it were available on the scan-tool screen in the data mode. Unfortunately, this information is not always available, and this “glitch” may occur faster than the scan-tool’s update capability so the voltage jump would be missed. Therefore, a digital multimeter must be used to monitor this voltage. This is of the utmost importance in diagnosing the sudden-neutral condition. This voltage should be monitored when the neutral condition occurs by placing the multimeter’s positive lead to computer terminal 30 if it is an EEC-IV system, as illustrated in Figure 2, or to terminal 64 if it is an EEC-V system. This wire is light blue/yellow on all applications except vehicles with the CD4E. On these the signal wire is red/black. Now, here is where this gets a little involved. The negative lead of the multimeter should be placed at the MLPS signal-return ground terminal at the MLPS. The reason is that the ground circuit for the MLPS can be shared by as many as FIVE other sensors, as seen in the wiring diagram in Figure 2. This means that there are factory splices in this ground circuit. If you check this ground at computer terminal 46 for the EEC- IV or computer terminal 91 for the EEC-V, the ground may check good but could be bad at the MLPS if there is a problem on the MLPS side of the splice, as also can be seen in the wiring diagram in Figure 2. The ground-circuit wire for 1989-90 F- and E-series trucks is black/white; all other vehicles use a gray/red ground wire except for CD4E applications, on which the ground wire is black/blue. Once the multimeter is connected to these circuits, as seen in Figure 3, place the meter where it can be seen while driving. When the transmission suddenly neutrals, be sure to have someone observe the multimeter, or use the meter’s MIN/MAX feature to record the highest and lowest voltage readings that occurred in the circuit. If the voltage jumps toward 3 volts as shown in Figure 3, and at that very moment the transmission neutrals, either the MLPS is faulty or the MLPS ground circuit is poor. Under normal conditions, this voltage reading SHOULD NOT CHANGE! When the voltage jumps toward 3 volts, this indicates a neutral-shift- lever position to the processor. This confuses the computer’s logic system, and therefore the computer is unable to fire the shift solenoids correctly (I think), and – BAM – you have a sudden-neutral condition. Why does the voltage jump because of a poor ground? The poorer the ground, the higher the resistance will be in that ground circuit. The higher resistance will cause the voltage in the overdrive or drive position to rise toward the 5-volt reference voltage, much like putting a bend in a garden hose would raise the pressure in the hose behind the bend. Ground- circuit integrity can be verified by placing the positive multimeter lead to the MLPS ground terminal at the MLPS and the negative multimeter lead to the negative battery post, as seen in Figure 4. With the multimeter set to DC volts and the engine running, the maximum voltage should be 0.1 volt. If more than 0.1 volt is seen on this ground circuit, it is NOT a good ground. In order to correct this condition, cut the ground wire close to the MLPS, attach it to a known good ground and recheck as previously described. Two things must be remembered here. One is that the return electricity will seek the path of least resistance. This path MUST be the ground circuit, NOT your multimeter. That’s why you should see a maximum of 0.1 volt on any 5-volt-reference ground circuit; 0.3 is acceptable on a 12-volt-reference voltage supply. The second thing to remember is that most electrical- fault phone calls I receive on the ATSG helpline are ground-related problems, so be sure to use the voltage-drop method of checking grounds as described. It may help to prevent you from falling into this trap..." transonline site is gone, but was able to save Figures 1 & 2

Source: by Pete L via miesk5

DTC 67 & DTC 634; Manual Lever Position/Transmission Range (MLP/TR) Sensor Pin-Point Test in 92-96; from Ford EVTM; "...Check the resistance of the MLPS: The resistance of the MLPS (pins 30 and 46).." read more Source: by jaa

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DTC 32 or 326; "...DTC 32/326 typically means that the EGR valve is not fully seated. This can be due to a bad EGR valve, vacuum trapped in the EGR hose, a clogged EVR filter, or a bad EVR solenoid. It is also important to note that if you have an exhaust ventilation system hooked up, that this can also cause an inaccurate reading. Try disconnecting the system and retesting..."

Source: by tomco-inc.com

DTC 32; "...Continuous Memory DTC 332 indicates the EGR valve did not open with the engine stabilized and the EVR solenoid duty cycle present sometime during vehicle operation. Possible causes: "...Obstructed or cracked hose to EGR valve,Icing, Damaged EGR valve, Damaged EVR solenoid harness..."

Source: by Ford via SigEpBlue (Steve)

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DTC 34 - EGR voltage above closed limit - Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the ****** side of the EGR by mouth. the egr is not closing properly which can cause detonation. remove the egr and clean off any carbon built up on it with carb cleaner and a brush if necessary.

Source: by miesk5 at Ford Bronco Zone Forums

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DTC 35; in KOEO - EVP too high or shorted to power poss open signal return or short to power; in KOER - RPM’s too low to test EGR; EVR-EVP sensor signal is/was high. Read MORE on Testing EGR Valve Position Sensor (EVP) & EGR Vacuum Regulator (EVR); also called EGR Vacuum Solenoid

Source: by miesk5

DTC 35; "...after doing the checks again and the EGR valve and solenoind seemed to be functional I pulled off the EGR valve and when I had it removed I found I could move the tube very easily. Well to make a longer story short, I replaced the tube, made sure it was tight at the manifold this time and now no more code 35..."

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KOER;

DTC 12 can't control engine RPM high RPM self test; vacuum leak, TB base idle off, idle air valve dirty or bad, EGR stuck open. Check the IAC valve port in TB for Sludge; Suspect throttle body coking

DTC 21 ECT out of self test range 0.3 to 3.7 volts; "... ECT is bad, engine not warmed up, bad thermostat, low coolant..Coolant is less than 50 deg F for KOEO, or less than 180 deg F for KOER, or greater than 250 deg F for either. If coolant temp is in proper range, suspect ECT sensor or it's connector/wiring..." read more

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DTC 22 or 126 indicates the Manifold Absolute Pressure (MAP)/Barometric Pressure (BARO) sensor is out of Self-Test range. Correct MAP/BARO range of measurement is typically from 1.4 to 1.6 volts. Do NOT use an ordinary voltmeter to check a Ford BP/MAP sensor because doing so can damage the electronics inside the sensor. This type of sensor can only be diagnosed with a DVOM that displays frequency, or a scope or scan tool. Also make sure engine manifold vacuum is within specifications at idle. If vacuum is unusually low due to a vacuum leak, ******** ignition timing, an exhaust restriction (clogged converter), or an EGR leak (EGR valve not closing at idle). A low intake vacuum reading or excessive backpressure in the exhaust system can trick the MAP sensor into indicating there is a load on the engine. This may result in a rich fuel condition. A restriction in the air intake (such as a plugged air filter), on the other hand, may produce higher than normal vacuum readings. This would result in a load low indication from the MAP sensor and possibly a lean fuel condition. Possible causes: circuit open between sensor vehicle harness connector and PCM. circuit shorted to VREF, SIG RTN, or GND. Damaged MAP sensor. Vacuum trapped at MAP/BARO sensor. Unusually high/low barometric pressure. Kinked or obstructed vacuum lines (MAP). Basic engine (valves, vacuum leaks, timing, EGR valve, etc.). High atmospheric pressure. Damaged PCM. VREF circuit open at MAP sensor. SIG RTN circuit open at MAP sensor. The pinpoint test directs you to check the voltage to the MAP sensor. With the MAP sensor connected, use paper clips to back probe the MAP connector so you make contact with the terminals inside the connector by inserting the paper clips into the bak of the connector. This allows you to get voltage readings while the connector is plugged in. The other option is to use straight pins to pierce the insulation of the wires. First check the voltage of the outer two wires of the MAP connector by connecting a voltmeter to the clips or pins you have inserted. You should see 5 volts with the key on. This is the power to the sensor. The BLK/WHTwire provides a ground called Signal Return (SIG RTN on EEC), it will show 0 volts with the black probe on negative battery terminal. The 5 volts VREF (ON EEC) (Reference Voltage) is supplied on the ORG/White wire. The Signal the computer reads is on the middle wire, DK BLUE/-Lt GRN (MAP on EEC). The correct MAP/BARO range of measurement is typically from 1.4 to 1.6 volts on the Signal (middle wire). If any of the voltages are out of range, there is a wiring problem that needs to be tracked down and repaired. These three wires all go back to the computer. The signal wire (middle) is the only one not shared by other sensors, it goes straight to the computer. The Signal Return and VREF are also provided to other sensors..." Read More Source: by miesk

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DTC 65 with E4OD - cycle OD cancel switch after engine ID is received in KOER or Check intermittent HO2S (signal or ground)

Source: by miesk5

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DTC 77 system failed to recognise brief WOT dynamic resistance test. Need to press gas pedal during KOER; Operator didn't execute WOT when told to during self test.

Source: by miesk5