Intermittant starting problem, have codes

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nelbur

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My '86 bronco has an occasional starting problem when hot. There is no spark and it smells of gas. The truck never stalls once started, and it will start when it cools down. I thought it was the ignition module so I replaced it. After a few weeks it started doing the same thing again. I have pulled the codes and got 11, 12, &15. I understand that 11 = Pass, 12 relates to idle rpm, and 15 is ROM test failed. I don't know what the ROM test is all about, but I don't see how any of these codes could relate to my starting problem. Does anyone have any ideas about what could be causing the hot start problem? I have just tried to clean the contacts on the coil and the main plug into the ignition module. If I get much more frustrated, I will likely just replace the coil and the dohickey in the distributor. Which should I try first?

 

Seabronc

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Do the doohickey :) /emoticons/[email protected] 2x" width="20" height="20" /> first, it is called a pickup. It is common for that unit to fail when hot and work when it cools back down.

Good luck,

:)>-

 

miesk5

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yo,

As our friend here, Fred advised...that is the usual suspect!

If it helps, but still have same issues;

DTC 15 Engine Control Module (ECM, EEC) Failure Symptoms, & other makes (part ad); DTC 15 Engine Control Module (ECM, EEC) Failure; "...Check voltage and ground at ECM connector. Voltage should be no more than 0.5 volts less than the battery voltage. Remove the ECM fuse. A digital volt ohm meter (dvom) or “Hot box” must be used to check all relays, solenoids, and injectors for short circuits. A short circuit will destroy the new ECM and will void the warranty. Check engine harnesses and connectors for corrosion and damage. Wiggle cables while car is running to see if a fault occurs. Power must always be off before beginning any work on the ECM. Symptoms of ECM Failure: No start/hard start; Engine stalling; Check engine light on; Erratic idle speeds; Rough idle / engine surging..."

Source: by CARDONE® cardone.com

Possible causes:

battery or PCM was disconnected

battery cables loose or poor connections

battery discharged

KAPWR circuit open- CHECK THE KAPWR ckt using this 86 EVTM Diagram by Ford via Ryan M; Pin 1 gets power via Y (Yellow) Wire thru a Splice 174, then thru Fusible Link N, and then to starter Relay, and then to batty + terminal.

& more Location pics in an 85 & 89 (between the starter relay and alternator)"...the first two pics are of an 89 5.0. because of the loom i wasnt able to trace the wires...The second pic is at the starter relay to show you a fusible link wire (the green wire in my fingers you can see at the eyelet there is a black plastic block). the third pic is of my 85. i think that big block is another style fusible link ford used on older stuff (but im not sure)..."

Source: by shift1313 (Matt) at Ford Bronco Zone Forums re it is in Chris B's 86

DTCs not cleared from a previous vehicle repair

EEC

===============

DTC 15 No keep Alive Memory power;

O = KOEO test key on engine off - No keep Alive Memory power (pin 1) or bad Electronic Control Assembly (EEC, ECA Processor);

M = in memory - after separator(10) in KOEO test- Keep Alive Memory (KAM) (pin 1) was interrupted

929

by Tomco Inc. tomco-inc.com

Now going to Ryan M's info;

EEC pin 1 is KA PWR also called KAPWR – Keep Alive Power

See it @ Connector Pin Outs, Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8; miesk5 Note, see his Connector Pin Diagram Link above)

Source: by Ryan M (Fireguy50) at http://fordfuelinjection.com/truckpinouts.html

For the EEC Connector

Connector Pin Diagram & Overview

eec04.gif


Source: by Fireguy50 (Ryan M) at http://fordfuelinjection.com/?p=3

TEST:

CHECK BATTERY TERMINALS

Inspect the battery cables for loose connections, corrosion.

Are the battery terminal connections in good condition?

Yes No

KEY OFF. Battery terminals are OK. GO to REPAIR battery terminals as necessary.

CHECK KEEP ALIVE POWER (KAPWR) TO EEC

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test. We're checking PIN 1

Measure voltage between KAPWR circuit at the PCM harness connector and ground.

While observing digital multimeter, grasp the EEC harness and wiggle, shake or bend a small section (really, this is Ford's Wiggle test)

Does the voltage reading indicate less than 10.5 volts?

Yes - ISOLATE and REPAIR open circuit.

No - open in KAPWR harness circuit detected. GO to CHECK FOR REPEAT OF DTC 15

Start engine and allow it to reach operating temperature.

Run Key On Engine Off Self-Test.

Retrieve Continuous Memory DTCs.

Is DTC 15 still present?

Yes - REPLACE PCM

No - drive and re-test;

do the KOEO = Key On Engine Off portion first &

Remember to have engine @ Normal Operating Temperature before doing the KEY ON ENGINE RUNNING (KOER) portion

Post Codes by; KOEO and

KOER

 

BroncoJoe19

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Isn't there a dohicky test where one sprays a coolent spray on it? Cryodiagnostic testing? I think they use those keyboard duster sprays.

 
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nelbur

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Thanks for the ideas guys. I have bought the pickup dohicky and will install it as soon as it stops raining. The Zone had it for $21. I believe I paid about $55 for the genuine Ford one about 10 years ago, back when a dollar was worth something.

I like the idea on cooling the distributor with a duster spray. I've been raising the hood and waiting. Sometimes after waiting, I am not a patient man, it would still not be ready, and I would start fooling around with the plug on the end of the ignition module. On occasion, that seemed to help. I am not sure if this plug is available as a part or not but if the pickup does not solve the problem, I'll investigate.

Miesk5, Thanks for the code info. If I understand correctly, the 15 code suggests that the engine control module has a problem. Is this the computer, to those of us who don't speak Service Talk? I believe I would like to erase all codes and see if they reappear. How does one erase the codes on these old trucks?

Thanks all. I will get back with the results when it warms up enough to be sure.

 

Rons beast

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We used to use freon to cool those things way back when we didn't know how bad the stuff was for the environment. (and it wasn't so expensive).

The ign module is the other dohicky on the side of the distributer.

Miesk5's check was for the circuit. To test and see if there was true and correct voltage to the module.

If not there may be a circuit and/or wire problem. If wiggling the wires and connectors produce a drop in voltage then there is a wire problem. (let's all hope not!)

 

miesk5

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yo N,

yw

re; "...the 15 code suggests that the engine control module has a problem. Is this the computer, to those of us who don't speak Service Talk? I believe I would like to erase all codes and see if they reappear. How does one erase the codes on these old trucks?..."

Yes it Could be the Computer, but that is the last resort in the pin-point test procedure from Ford.

Go thru da drill; check batty voltage @ posts

"...a normal battery that is fully charged produces 12.6 volts, not just 12.0 V. (Remember, when measuring battery voltage, everything in the car should be off, or the battery should be disconnected. Voltage measurements are always "no load" measurements unless the battery is being tested for it's performance under load)..."

Source: by Gordon via miesk5

With the engine running at 2000 rpm, check the alternator output voltage. The voltage should be between 13.0 and 15.0 volts.

etc.

Clean the posts while you're there; inspect/clean terminals on both posts; check wire strands leading into the terminals for corrosion- if it really bad corr. then peel a little insulation back on wires and clean

the wire connection inside the battery terminal connector corrodes easily. This will cause a voltage drop in the cable and result in low voltage being supplied to the starter. You can check for voltage drop in the cable using a digital voltmeter. Connect the negative probe of the voltmeter to the negative battery post (not the battery terminal connector). Then connect the positive probe to the starter case and crank the engine. The voltage reading should be less than .5 volts. A higher reading means there is resistance in the cable or the battery terminal connector. Clean the cable end and the battery terminal connector and test again. If the voltage reading is still higher than .5 volts, replace the cable and the battery terminal connector.

Check ground cables toengine/frame/firewall/passneger side fender apron near batty

To Clear Codes; Disconnect Battery negative post terminal for five minutes or more (preferably 15 minutes)

drive the vehicle for at least ten miles to allow the computer to relearn the values for optimum performance.

 
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nelbur

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I replaced the pickup coil (dohickey) and figured I had the problem solved. However, after running it long enough to warm it up, I shut it down. When I tried to start it about a half hour later, it just cranked and smelled of gas. I messed with every connector around the distributor and the coil with no success. I just had to put the hood up and wait for it to cool down. Since I have already replaced the ignition module, the only component I can think of that might be causing the problem is the coil. I will replace it tomorrow and if that doesn't help I will start checking the wiring. The problem never happens at home where I have the tools and the time to check things over.

The battery is new and the starter cranks over rapidly. I just don't think I have any spark because I smell raw fuel and when it starts it acts flooded. I feel sure that the problem is not under the dash since it responds to opening the hood and cooling it down. I welcome all suggestions. I feel like a real mechanic, just replacing parts until the problem goes away.

PS The comment about the grounds is interesting. Do the ignition components use the same ground as the starter, or do they have a separate ground of their own, and if so where is it?

 
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Seabronc

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PS The comment about the grounds is interesting. Do the ignition components use the same ground as the starter, or do they have a separate ground of their own, and if so where is it?
If it turns over, you probably don't have a grounding problem. Ground for the ignition is to the engine block which is also the same for the starter. However, since the distributor grounds to the block, you might want to try marking it's position and then loosen the hold down bolt and twist it around a bit to polish it's contact to the block and then put it back in it's original position.

Spark should be easy to check by pulling a plug wire and checking to see what the arc to the block looks like.

Good luck,

:)>-

 

Seabronc

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By the way, I don't believe you have mentioned which engine you have 302 or 351?

:)>-

 
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nelbur

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Guys, I think I have found the problem. The coil did not fix it, but I ran the truck in my driveway until it heated up. Let it heat soak for about 10 minutes, and tried to start it. Fortunately it would not start (How often can you say that?) This is a 302 EFI, and after Miesk5 jogged my memory about grounds, I remembered that there is a small wire on the neg. battery terminal that grounds the computer. I found a crimp type butt splice on the wire, probably something I did many years ago when I replaced a corroded neg. battery cable. I recrimped the butt splice using a crimper I have that drives a pin about half way through the crimp for a very good contact. The truck started right up. I have been using it all day with no further problems. It will be a few days before I know for sure it is fixed but it looks encouraging. I'll solder the butt splice the way it should have been done the first time. Thanks to everyone for thinking through this with me. Sometimes one needs to be pointed in another direction.

Sorry I didn't make clear what engine I had. I have tried to put it in my signature but I am not sure if I figured out how to do it or not.

I believe the trouble code 15 was trying to tell me that the computer was having problems with the ground, but it was too dumb to make it clear to someone as dumb as I am. The OBD II version has proven to be much better at pointing towards a problem on my other vehicles. Of course the new engines have two or three times the sensors. The old Bronco doesn't even have an oxygen sensor.

 
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nelbur

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Finally figured it out. Soldering the ground to the computer solved A problem, but not THE problem. After about two weeks the problem returned with the next hot weather. Leaving the hood up for 10 minutes to let it cool a bit, would always let it start. With a well grounded computer it could now remember past faults. I got a 21, ECT out of range (engine coolant temp. sensor) and 51, ECT input too high. I changed out the ECT and the problem has not recurred during the current hot spell.

I guess the ECT, which is on a pipe type riser on top of the engine that feeds the heater and throttle body hoses, Would go above some critical temp. reading from the engines heat soak, and the computer would refuse to let the engine start until the temp. reading dropped below that level. The actual temps. were normal, but the high reading ECT apparently had the computer asking, "Why is this fool trying to start this overheated engine." I didn't know this first gen. EFI was that smart. I would have bet money that no sensor reading would keep the engine from starting.

 

Seabronc

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I hate to say it, but that is the very reason I love the old carbed engines. The higher tech something is, the more susceptible it is to bad input to the computer. I have never had my carbed engine refuse to start because some sensor was giving bad input :rolleyes: . The computer God gave me is capable of reading the gages and determining if I have a problem :) /emoticons/[email protected] 2x" width="20" height="20" /> and it doesn't turn off the key because the temperature sender is bad. A case in point that caused several hounded people to die was the Air France flight from South America to France that went down because the computers didn't know what to do and the flight crew was so dependent on the computer flying the airplane that they couldn't sort out what was happening.

Good luck, and thanks for getting back with the solution.

peace.gif


 
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