1987 with Code 42
Thread Starter
Cruising
Joined: Apr 2017
Posts: 14
Likes: 2
1987 with Code 42
I recently had a Corvette shop install a turn signal flasher in my 1987 Corvette. When I got it back, the SES light was on. I asked the shop if they could have possibly left a wire disconnected. They said no. I realize the turn signal flasher is above the computer just above your feet on the passenger side. I did not install this myself and went to a professional because I have been known to be clausterphobic in the past. It seems too coincidental that the light was not on before I had the flasher changed and is on right after the work is done. So I am going to have to diagnose this and fix this myself. Any suggestions what could have been damaged or disconnected? I pressed the plug on the ECM and started the car. The light did not come on for 5 seconds. It normally comes right in after starting the car. Do you think it is the ECM or its connector? Or could it be a wire that got disconnected? Any help is deeply appreciated. Many Thanks.
Melting Slicks
Joined: Nov 2016
Posts: 2,256
Likes: 3,082
From: So Cal
2023 C4 of the Year Finalist - Unmodified
Code 42 can be set by the "Set Timing Connector" being disconnected. Did the shop happen to check the ignition timing for some reason such as emissions testing or something?
The Set Timing Connector is a single tan/blk wire connector in the vicinity of the wiper motor. Be sure it isn't disconnected. The connector is shown in the diagram above in the "Bypass" circuit adjacent to the ECM, although the actual connector is in the engine compartment.
The Set Timing Connector is a single tan/blk wire connector in the vicinity of the wiper motor. Be sure it isn't disconnected. The connector is shown in the diagram above in the "Bypass" circuit adjacent to the ECM, although the actual connector is in the engine compartment.
Thread Starter
Cruising
Joined: Apr 2017
Posts: 14
Likes: 2
The car runs the same as it did before bringing it to the shop to have the turn signal flasher changed. Only now the SES light is on and it gives code 42. I changed the ignition module 2 years ago when the car would suddenly turn off and back on while driving. Replaced it with genuine GM part. That was not the problem. At that time I got codes 33, 42. Turns out that was a bad MAF power relay. Have not had code 42 until I brought the car into the shop. I am going to do as your diagram suggests and disconnect the 2 ECM plugs and reseat them and see if that helps. Also, I know that one of my plugs going to the distributor has a broken retainer clip. I will try reseating that too and get back with you. I just seems too coincidental that I did not have this issue before the shop replaced the turn signal flasher with is located on top of the ECM. Many Thanks.
Thread Starter
Cruising
Joined: Apr 2017
Posts: 14
Likes: 2
I don't think it is the ignition module. I changed it 2 years ago with a ACDelco one when I had previously got a code 42. When I did, it didn't make a difference. I really think this has everything to do with the shop changing the turn signal flasher which is above the ECM. I don't really understand the above schematic and the shop did not take responsibility for this situation, so I have to figure this out myself. What should I do first? Thanks.
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