After installing stereo, engine has miss???

[coach]

Hello all, I just had an aftermarket stereo installed in my GN and when I was driving home, the service engine light came on. I took it to my buddy who scanned it and it came up CODE 42. It says that the computer is in "LIMP HOME MODE". Ever heard of this? It lists 4 reasons, most had to do with spark, or spark control. It listed coil pac, ecu, etc. Has anyone ever seen this before? I noticed that the stereo guy run the amp wire inside the car right close to the computer. I am going to start with plugs and wires, what else???I need some BUICK EXPERTISE!!!
Coach

 

[Silver Fox]

Hello all, I just had an aftermarket stereo installed in my GN and when I was driving home, the service engine light came on. I took it to my buddy who scanned it and it came up CODE 42. It says that the computer is in "LIMP HOME MODE". Ever heard of this? It lists 4 reasons, most had to do with spark, or spark control. It listed coil pac, ecu, etc. Has anyone ever seen this before? I noticed that the stereo guy run the amp wire inside the car right close to the computer. I am going to start with plugs and wires, what else???I need some BUICK EXPERTISE!!!
Coach

What kind of music were you listening to on the way home from the stereo shop?

Seriously though, the amp wire may be sending some unwanted energy to the ECU. Or another thought...did the stereo shop guys take it for a ride to check for "ignition noise" and test drive it a bit too thoroughly (I always dial the boost way down when I have to leave the car with somebody at a shop or ship it)?

I'd try pulling that amp wire away from the ECU and see what happens then troubleshoot more if needed.

You might also check to see that they didn't leave any grounds disconnected.

 

[coach]

I did think about the "TEST DRIVE" after I picked it up, but he is pretty well known in our area and says it never left the shop. I already pulled the fuse from the amp wire to kill power to it and also disconnected the battery for a few hours to clear everything. I hooked it back up last night and it did the same. I was sent a list of things to do to troubleshoot CODE 42, so I will start there.

 

[cuda6pak]

What gauge is your amp wire? I ran my amp wire through the drivers side to avoid any issue with interference between the amp wire and the computer

 

[hrhoward]

Coach,
Did the installer come through the firewall with the amp power wire the same place as the ECM harness does? If so, maybe he disturbed some of the 20+ year old wires and connections.

 

[Devil Car]

Back in the day, I had a high power stereo system in my GN, and initially I ran the power to the amp near the ECM. I found that my car seemed to "forget" the learned calibrations often. After moving the power supply to the drivers side, the problem went away... It's possible that EMI is causing problems with your ECM.

Like others have stated, try moving the amp power supply wire to the other side of the vehicle, or even just disconnect it, then reset the computer and see if it happens again.

 

[coach]

Hello everyone. I found out it is much worse than we thought. I took it to my buddy at our local Buick garage. He called the shop and asked them what they did exactly. They told him that later in the day from the doors being open and the key on, they thru a battery charger on it. It spiked the module and maybe the ECM. It also might ahve cooked the spark timing box. They did agree to fix what is wrong , but that was when they thought it was only the module( $300.00). Monday morning will be very interesting after learning this over the weekend. Thanks to all.

 

[Daniel Jost]

i dont think that the ECM would have got taken out from that, they are very hard to wreck. Also why would charging the battery kill the ignition module? I charge my car all the time when working on it ??
,Dan

 

[coach]

engine module

i dont think that the ECM would have got taken out from that, they are very hard to wreck. Also why would charging the battery kill the ignition module? I charge my car all the time when working on it ??
,Dan

They had the key on and it spiked. I was told this by at least 2 service techs for Buick. Hooking up a charger can only be done with the car running or key in the off position. That is what they say. I hope you are correct and the ECM is ok. I hope the spark timing box is unharmed also.