Hi,
Yesterday I had to change the passenger side low-beam head light. I had to disconnect the battery and remove it since it was in the way. After I replaced the light and reconnected the battery, I got a check engine light. The car reversed fine but it struggles to move forward. The car was fine before I replaced the light.
Can any one suggest what is wrong with the car?
Thanks.
My first question is was there a chance you might have caused a short when removing the battery? If the vehicle starts ok then let the car run for a few minutes before trying to move. Some have to " re-learn" the factory settings in the ECU before they will run properly. That may not explain the check engine light. Have some one retrieve the codes.
Thank you, I think you are right on. I did go to the autozone and had had the diagnostics run and the following report came out:
ECM/PCM Internal Circuit Failure
Probable cause:
- Open of short circuit condition
- Poor Electrical Connection
- Failed ECM
This is the way I drove the car to the Autozone that is 3.5 miles from my house:
- Start the engine
- Put the transmission to “2”
- after the car picks up like 15mph shift to D3 and then to D4
- from there on it runs just fine
- When a stop signal comes, after stopping I repeat “2”, D3, and D4
I do not know if I had caused a short (atleast I did not see any sparks) but it did happen to me a year ago and somehow when the check engine disappeared (all by itself), everything became normal. I think the same condition got repeated.
The car still has the problem.
How do I reset the factory settings?
Please help.
Thank you
Did you disconnect the battery with the ignition switch ON (RUN)? If you did, that could be an “ut oh!”. I’m not sure if that applies to your car. Some car maker(s) warn that disconnecting the engine computer electrical connector with the ignition switch ON, can harm the engine computer. Would disconnecting the power supply (the battery) be equivalent? Good question.
Yes, I did remove the key from the car ignition before I worked on it. Thank you.
Read the beginning of this article. http://www.brakeandfrontend.com/Article/46474/battery_service__diagnosis.aspx
To prevent these kind of problems on todays vehicles, something like this should be used http://www.redhillsupply.com/KAS295A.htm
I have a feeling we’re going to get more and more posts that start with, “I disconnected my battery, what’s wrong with my car?”
Tester
Is there any CHANCE you momentarily connected the battery backwards??
No I did not. But I did find one of the connections was not very tight enough. The cable with the ring at its end that connects to the pin on the battery was a slightly loose. So saw this today and I lightly tapped on the ring so that it sat around the pin snuggly.
Just now I disconnected -ve terminal of the battery for about 5 minutes and reconnected it back. When I turn on the ingition to start the engine, the check engine light came on and it was blinking. I kept the engine running for another 5 minutes hoping if it would reset to factory settings. Then I turned off the engine and restarted. It did not help at all. Now the check engine light is continuously on as before and the car struggled to move forward.
Can any one suggest what else I could do? If not then I will take it to the dealer to look into but it hurts because it costs too much $$$.
Thanks.
Several auto parts stores (chains) will read the codes for the check engine light (symbol) for free (except in California). Get the codes read and bring them here.
An OBD II code reader is about $70, and you can use it many times. The price is less than a dealer’s one-time read. It’s very easy to connect and read an OBD II code reader, and it provides a lot of useful information. So, bring it on!
Hi, Thank you.
I went to the dealer to look into it and he could not read any codes off the ECM. Couple of technicians looked into it and they could not figure out any reason other than ECM failure (shorted). So they replaced the ECM ($1009+labor+tax) and it read immediately and everything started working normal. They had to reprogram the keys. I asked them for the old unit and they gave it to me (because no core return gains). I may try to sell it to some seller who refurbishes old units or give it to any one who is interested to kook into it for the sake of curiosity. For sure it ia a ECM failure that caused all the problems.
In future I would rather look into preventive care measures (a good article above by “Tester”) before jumping of repairs.
Your experience shows that troubleshooting is as much art as it is science; both art and science are needed in judicious amounts.
Thanks for the feedback.