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Car Computer ECM Questions and Answers

This category contains featured questions as examples. They relate to most vehicles.

Question: 1996 F350 7.3 diesel mileage: 116,000. OD light starts flashing every once in a while. Then transmission shifts rough. Took to transmission guy, he said transmission was fine; it was some kind of other problem Code he gave me was P1728. Ford dealer today told me code says slippage and need new transmission or overhaul $$$$$$. When you unhook battery, for few minutes, it resets itself and then the truck runs great, no problems with transmission shifts until the next time. I have found a lot of people on the Internet with same problem, haven't found anyone who had solution. Can you help?

Answer: P1728 indicates that the transmission is slipping. When the computer that controls the transmission detects a fault code like P1728, it will put the transmission into a "limp" mode. When the code is cleared and the transmission will function properly until the slippage occurs again. To resolve this problem, you will need to get your transmission overhauled.

Question: 1995 VW Jetta 2.0L mileage: 88,000. I have been experiencing problems with my check engine light. I have had the engine codes looked at and it was diagnosed as the 02 sensor. So, I have replaced it. Since then, I have also replaced all of my spark plug wires and my breather tube. I am currently at a loss. The light comes on about every other day and when it does come on the engine loses acceleration power and shutters lightly. It is drivable but the problem is very noticeable. It seems to me when it all goes wrong the fuel mixture is off so the engine over compensates and is either letting too much air in or it is letting too much fuel in. Any Suggestions? What do you think is the next best step?

Answer: Rescan the computer for fault codes. It appears that another component may have failed.

Question: 1995 Ford F150 5.0 mileage: 232,000. I had a long block installed at 204,000 miles. About 5,000 miles ago my check engine light came on, the code indicated it was the 02 sensor, so I replaced it. The light came on again 1500 miles later, again the code said it was the 02 sensor, so I replaced it. About 1500 later again the same story, so I got a different brand. This one lasted about 2000 miles and again the light is on and the code says it is the 02 sensor reading lean. What else could the problem be? Could it be giving me a wrong code? The code is 172.

Answer: The 0� sensor reading lean is probably caused by a malfunction in the fuel system, possibly a plugged fuel injector or a weak fuel pump.

Question: 1996 Ford Taurus LX 3.0 mileage: 74,000. Sorry, I had not read a lot the Q & A's when I wrote previously. Now that I have, I have another question. How do you scan the body control module? I have tried to purchase a "code reader" from an independent parts dealer and they said that I would have to bring my car to the dealership. Any help will be greatly appreciated.

Answer: Many independent auto service centers have the necessary equipment to read the codes on the body control module.

Question: 1992 Dodge Grand Caravan 3.3L mileage: 236,000. Just changed the rear main engine oil seal, after reinstalling transmission. It's stuck in limp mode (only reverse and 2nd gear available). I've tried: Disconnecting battery and waiting couple hours, Double checked wiring and harness connections, Fluid level (yes its the right type ;)) Shift cable Fuses and relay connections I don't get any trouble codes on the "check engine" light test other than 12 and 55 (12=recent battery disconnect, & 55 is End of info). Everything came apart and went together with no issues. I've done this a couple times in the past when tranny failed (gee I wish I had done the rear main THEN!) Any thoughts or suggestions? James

Answer: Drive the car until it is thoroughly warmed up. Stop the car and shut off the ignition. Turn the key on and off four times. This will clear the drive train computer and your transmission should function properly.

Question: 1991 Ford Taurus not sure mileage: 94,000.  Can you give me any information on the brain in the dashboard?  Like how to put it back together.  It has been at a garage for four months.  They said it was the brain and would cost over 500.00 dollars to fix.  I don't have that kind of money.  Any information would be greatly appreciated.

Answer: Are you sure there is something wrong with the "brain" (power control module - PCM) -- it usually does not go bad.  Most likely one of the components that feed the PCM or that the PCM controls is malfunctioning.

Question: 1999 Ford Ranger mileage: 106,000.  The check engine light came on.  I have a code 211 read out.  Cleared all codes now the only code is 157 MAF sensor low voltage.  998-hardcode fault confirms that it is not the ignition module. All sensors seem to check out ok.  What is more specific definition of 998? Could it be the PCM?  Or in one of the sensors? Computer seems to always go into open loop.  HELP!  PLEASE!

Answer: Code 211 is a profile ignition pick-up that means anything in the ignition system.  Since you have eliminated the ignition module, try replacing the ignition pick-up coil.  Code 998 merely is telling you that some hard codes have been set in the computer.  A Mass Air Flow Sensor can cause similar problems to the ones you are having.

Question: 1999 Lincoln Town Car mileage: 95,000.  Engine code displays bad # 2 fuel injector...replaced the injector but after about two miles same misfiring and sputtering under acceleration.  What else is wrong?

Answer: The injector driver in the computer may be causing your computer code.  Also, check the spark plugs and plug wires and if they have not been replaced recently, this could be a contributing factor to your problem.

Question: 1998 Ford f150 4x4 Supercab mileage: 75,000.  I have been trying to solve some error codes for a while.  I was getting all kinds of codes at first.  I realized that my vacuum reservoir was rusted out.  I have replaced it.  I cleared codes and drove it for a period of time.  I now get oxygen sensor errors 171 and 172 and 173.  I seem to have terrible mileage also.  After changing the vacuum reservoir, and still having O� codes, I thought I needed a new O� sensor.  With the new sensor in place and running the vehicle on the highway for 10 minutes, the service light comes on and stays on.  I returned the sensor assuming I had a bad one.  The new sensor seemed to help for a while but now the light comes on steady again after 10 min on the highway, always with O� sensor codes.  I have also noticed that the vehicle starts much better in cold weather (-20) than it does in warm weather (around freezing temp).  In warmer weather the engine seems to start - and then miss immediately, giving similar characteristics of a flooded engine until it restarts.  Any ideas would be appreciated.

Answer:   Check the fuel pressure regulator, as it may need to be replaced.  Also, check the fuel pump pressure because we have found that the fuel pumps in each of the tanks have proven to be rather high maintenance.
 

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