ECM codes

My Bronco is a 1992, 5.8l, E4OD. Had her since she was new. She's currently running great except for the check engine light comes on when I accelerate. I pulled the KOEO codes and got a bunch. 116 (ECT), 636 (Trans oil temp), 121 Throttle position), and 114 (Intake air temp). Since the light was coming on during acceleration, I went for the throttle body position sensor. I errased the codes, or at least thought I did by leaving the battery disconnected over night. Decided to check KOEO again, and had the same codes. Is it possible my ECM is throwing out false codes since she seems to be running good?

yo V,

WELCOME!

Lets, go through the Codes before suspecting the ECM (aka PCM, computer, EEC...);

DTC 121, 122, 123, 124, 125 & DTC P0122, P0123 & P1121 in TSB 94-26-4; "...The following is a list of vehicle symptoms which have been associated with the TPS, but can also be related to other vehicle components. Check engine light, Stalls, quits, hesitation/stumble, fast idle; To minimize the replacement of good components, be advised that the following non-EEC areas may be the issue: Excessive blow-by, PCV malfunction, Vacuum leaks, Fuel pressure, Throttle sticking or linkage binding. MANY VOLTMETERS WILL AUTOMATICALLY CHANGE RANGES WHEN MEASURING TPS OUTPUT FROM IDLE TO WOT. WHEN A VOLTMETER IS USED TO MEASURE TPS OUTPUT FROM IDLE TO WOT, THE METER SCALES OR CHANGES RANGES AUTOMATICALLY. THERE MAY BE AN ERRONEOUS METER DISPLAY UNTIL THE VOLTMETER HAS LOCKED TO THE APPROPRIATE VOLTAGE READING. THE ERRONEOUS METER DISPLAY DOES NOT REPRESENT A DEFECTIVE TPS. NOTE: IT IS RECOMMENDED THAT THE "RANGE LOCK" FEATURE ON MANY METERS BE SET FOR CHECKING TPS VOLTAGE..."

Source: by Ford via http://www.tccoa.com/articles/mn12-techinfo/tsb/tsb-94-26-4.pdf

Throttle Position Sensor Testing, Replacement and Adjustment

by Seattle FSB

DTC 116 Engine coolant temp. higher or lower than expected Possible causes: Low coolant level (ECT), Ambient temperature below 10°C (50°F) (IAT), Faulty harness connector, Faulty sensor

Source: by fordbronco1995

 

DTC 116 to 118 ECT Troubleshooting & Possible Causes; "...The ECT sensor is a thermistor, basically a resistor that changes voltage accordingly to temperature changes. It provides a reading that's used by the EEC to change fuel delivery at engine startup to reduce emissions and monitors the temperature of the engine. If you see some rust in it clean it by sanding the surface using a fine grit sandpaper, Also check the connector and wiring..."

DTC 636 Transmission Fluid Temp (TFT) higher or lower than expected; "...Can be caused by a bad connector or harness (an open circuit, or short to Ground / Batt), or the transmission was overheated. Once you remove the pan locate the sensor in the valve body and remove the electrical connector very carefully. The sensor is about the size of a pen cap. To remove the sensor carefully unlock the stop tab and twist it, pull down to remove it. It comes out before a full quarter turn is made. Put it back in the reverse order. When you get the sensor to come out be prepared to catch the trans fluid that follows behind it, you will get less than a quart out of it. It is located in da Pack between Converter Clutch Control (CCC) Solenoid & the Coast Clutch Solenoid. try the connections first. They are usually the root of the problem..."

DTC 112 to 114, Intake Air charge temperature sensor (ACT or IAT)Troubleshooting & Possible Causes; "...Codes 112 to 114 will set a IAT sensor code in the EEC, remove and inspect the sensor it could get contaminated by engine oil , K&N oil or dust. Clean the sensor with isopropyl alcohol. If the sensor still fails replace the unit..." Intake Air Temp (IAT); (Air Charge Temperature [ACT] prior to 1992)

"This measures the temperature of engine, and has a great impact on fuel ratio. This makes simple work of enriching the mixture on start up, overheating, and full throttle fun. It also allows us to lean out the mixture at certain times, to shorten the time it takes to warm up the engine helping us get great fuel economy. The Engine Coolant Temperature (ECT) sensor is a thermal transistor, which means it allows less electricity to pass through the sensor the warmer it gets. The ECT receives the “Signal Return” voltage from the EEC, then allows a certain amount to return back to the EEC. Because the ECT is in direct contact with the engine coolant flow it changes resistance in response to the temperature of that coolant. The ECT is third in command in the hierarchy of EFI sensors, this means this sensor is very important when calculating fuel ratios and timing curves. This is because of simply chemistry; fuel and spark are constants in the equation. Air is the biggest variable in combustion; it changes density greatly over a range of temperature. So keeping track of the changing temperatures of the incoming air and the engine in which it is burnt becomes very important. But due to its simplicity of design, the ECT is rarely at fault when problems occur. The engine temperature must be greater than 50°F (10°C) to pass the KOEO Self-Test and greater than 180°F (82°C) to pass the KOER Self-Test. To accomplish this, the engine should be at normal operating temperature...Before you start blaming the engine coolant temperature sensor and replacing it make sure the rest of the coolant system is in good condition. All of the following items will affect the ECT: *Coolant level *Radiator Fan *Water Pump *Water Pump and Fan Belts *Thermostat *Base Timing *Engines general condition *Harness and wire general condition..."

Source: by Ryan M (Fireguy50)

Consider Ford Fuel Injection and Electronic Engine Control: How to Understand, Service and Modify, 1988-1993; & Ford Fuel Injection and Electronic Engine Control: How to Understand, Service, and Modify All Ford-Lincoln-Mercury Cars and Light Trucks, 1980 to 1987 by Charles Probst

avail @ BARNES & NOBLE, AMAZON, E BAY, ETC.

All great information, and I'll check that out. I guess my main question is why the codes don't clear. As I said, I swapped the TPS. Here's the sequence of events.

KOEO codes 116, 636,121 and 114

Disconnected battery

Changed TPS

Next day, reconnected battery, did not start engine. Ran KOEO again, and got the same error codes. Shouldn't those have cleared?

Thanks again.

yo,

This is by Ford;

"...

The Key On Engine Off and Engine Running Self-Tests detect faults that are present at the time of testing. Faults that occur only when the vehicle is operating or intermittent faults that have occurred in the last 80 warm-up cycles are detected during Continuous Self-Test, stored in Continuous Memory an displayed during Key On Engine Off Self-Test.

Key On Engine Off Self-Test
Special Notes:

• Continuous Memory Diagnostic Trouble Codes (DTCs) recorded in this step will be used for diagnosis after a PASS code 11 or 111 is received in both the Key On Engine Off and the Engine Running Self-Tests.
• Deviation from this procedure may cause the output of false DTCs.

How to Clear the Continuous Memory
 

Note: Do not disconnect battery to clear Continuous Memory. This will erase the Keep Alive Memory (KAM) information which may cause a driveability concern.

1. Run the Key On Engine Off Self-Test.

1. When the DTCs begin to be displayed, deactivate Self-Test:

• STAR Tester: Unlatching the center button (up position).
• All others: Remove the jumper wire from between Self-Test Input (STI) connector and the Signal Return Pin of the DLC.
• Scan Tool: Pushing the STOP button.

1. Continuous Memory will be erased in the PCM. 
   

How to Clear Keep Alive Memory (KAM)
The PCM stores information about vehicle operating conditions and uses this information to compensate for component tolerances. When an emission related component is replaced, Keep Alive Memory (KAM) should be cleared to erase the information stored by the PCM from the original component.

To clear KAM: Disconnect the negative side of the battery for a minimum of five minutes.

After KAM has been cleared, the vehicle may exhibit certain driveability concerns. It will be necessary to drive the vehicle 10 miles or more to allow the processor to relearn values for optimum driveability and performance. (Distance is dependent on the vehicle application.)..."

The Codes should have cleared; unless there is a rechargeable battery in the Bronco that keeps CM and KAM on.  Some use recharge. battery as part of an alarm system etc.

I have a 96 bronco Eddie Bauer 5.8 check engine light a code po402 i changed the dpfe sencer it starts stumbles then stalls out need help please thanks!

Ivansbronco said:

I have a 96 bronco Eddie Bauer 5.8 check engine light a code po402 i changed the dpfe sencer it starts stumbles then stalls out need help please thanks!

Click to expand...

Please open your own thread on this subject.  This is what is called thread hijacking,  A thread is for the originator and any comments that apply to his/her particular problem.

Thanks,

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