CODE 42
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Joined: Feb 2001
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From: Northern California
CODE 42
My 88 has a code 42. The car hardly runs. I do not have a scanner I just got the code from the diagnostic mode. It looks like it might be the electronic spark module. Any other ideas would sure be appreciated.
Thanks,
Bob
Thanks,
Bob
Burning Brakes
Joined: Oct 1999
Posts: 843
Likes: 2
From: Nashua New Hampshire
Re: CODE 42 (Bob 57)
First, look for the simple things.
Got my car back from the mechanic recently - some engine work incl. changing rotor, etc. Car ran nice, but didn't seem 100%. Nothing I could point to as being wrong, but it just didn't seem to be running at it's best. No SES light or anything.
I had ordered Diacom. When it came and I hooked it up, every reading looked pretty reasonable. No problems there. Then I had it check the codes. A 24 and a 42 were stored. I look up 24, it's vague. I look up 42, and it says the ignition module failed the startup diagnostic. I had other things to do and ignored it at the time.
A few days later I was reroutine plug wiring, and I noticed the 3-wire connector going into the distributor (to the ignition module I believe), was sitting crooked. I push it in properly. Started the car, hooked up Diacom, and my 24 and 42 codes were gone. Took for drive. Sounded smoother, and it was pulling the 100% I expected of it.
So check the wiring going into the distributor first. I don't know what's inside, but perhaps a connection inside the distributor has come loose.
Got my car back from the mechanic recently - some engine work incl. changing rotor, etc. Car ran nice, but didn't seem 100%. Nothing I could point to as being wrong, but it just didn't seem to be running at it's best. No SES light or anything.
I had ordered Diacom. When it came and I hooked it up, every reading looked pretty reasonable. No problems there. Then I had it check the codes. A 24 and a 42 were stored. I look up 24, it's vague. I look up 42, and it says the ignition module failed the startup diagnostic. I had other things to do and ignored it at the time.
A few days later I was reroutine plug wiring, and I noticed the 3-wire connector going into the distributor (to the ignition module I believe), was sitting crooked. I push it in properly. Started the car, hooked up Diacom, and my 24 and 42 codes were gone. Took for drive. Sounded smoother, and it was pulling the 100% I expected of it.
So check the wiring going into the distributor first. I don't know what's inside, but perhaps a connection inside the distributor has come loose.
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Joined: Feb 2001
Posts: 79
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From: Northern California
Re: CODE 42 (gh86E)
Thanks Greg! First thing after work I'll check all distributor wires. I'm still open for any other ideas. As of right now, the car is not drivable. Runs but dies constantly.
Bob
Bob
Burning Brakes
Joined: Nov 2000
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Re: CODE 42 (Bob 57)
Hey Bob, the ESC only operates the Knock sensor, when I was trouble shooting my car I could unplug the the ESC and car still ran (idled, and rev'd, but not driven) ok. There are some really great trouble shooting books out there, I found and bought two at Barnes and Knoble (not Chilton or Haynes). Have you replaced the ECM yet? Most of us with older C-4's have and the ones that haven't will soon. I replaced mine about a month ago. Paid less than $90.00 at Kragen for rebuilt ECM and car runs fine know.
Burning Brakes
Joined: Nov 2000
Posts: 855
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Re: CODE 42 (Bob 57)
It'll be later this evening but I could dig out those trouble shooting books and see what they say about trouble shooting the ESC. It was about a month ago that I thought mine was bad and trouble shot it. All you need is a digital mulitmeter. It was not that difficult to trouble shoot.
Drifting
Joined: Mar 2000
Posts: 1,630
Likes: 1
From: Woodstock GA
Re: CODE 42 (Rick86)
Code 42 would be EST bypass, it's the code you would get if you unplug the tan and black wire to set ignition timing. The car would have a low idle maybe even stall and have a lack of power. Check your bypass connector by the wiper motor and also the distributor connection coming off the distributor sometimes that harness can get pinched under the distributor cap and cut through or sometimes it can get pinched under the distributor. If you find the bypass unhooked just pluging it in will not get it working in most cases you will have to shut the engine off and restart it to work normal, but let us know.
David Fulcher
David Fulcher
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Joined: Feb 2001
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From: Northern California
Re: CODE 42 (David-F)
David,
I followed the procedure on code 42. I disconnected the ECM, put the ohm meter from the white wire to ground, with key on. It said I should have less than 500 ohms. I measured an open. The troubleshooting chart led me to either an open circuit or ignition module. I replaced the ignition module. Same problem. The black and tan wire for the bypass appears fine. Putting lots of time into this but I'm not giving up!
I'm all ears for suggestions.
Thanks, Bob
I followed the procedure on code 42. I disconnected the ECM, put the ohm meter from the white wire to ground, with key on. It said I should have less than 500 ohms. I measured an open. The troubleshooting chart led me to either an open circuit or ignition module. I replaced the ignition module. Same problem. The black and tan wire for the bypass appears fine. Putting lots of time into this but I'm not giving up!
I'm all ears for suggestions.
Thanks, Bob
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Burning Brakes
Joined: Nov 2000
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Re: CODE 42 (Bob 57)
Bob 57 sounds like you bought one of those books, which one did you get, I have the "Chevy TPI Fuel injection Swapper's Guide" and "How to Tune & Modify Chevrolet Fuel Injection" both are great and highly recommended. The later book shows to check for 5 volts at tan/blk wire (you did that right), if you have 5 volts connect a digital dwell meter to point (white) EST wire. note the dwell reading. 0 or 90 replace the ignition module (you did that) other than 0 or 90 replace the ECM.
Sounds like ECM (I ended up replacing the module and it didn't work, but ECM did the trick)
Sounds like ECM (I ended up replacing the module and it didn't work, but ECM did the trick)
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Joined: Feb 2001
Posts: 79
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From: Northern California
Re: CODE 42 (Rick86)
Rick,
No I did not buy the book. I had a friend a "Corvette Care" in Rancho Cordova photocopy me one page of troubleshooting. Got the problem solved now. If you tapped on the ECM everything cured itself! Bad ECM. All OK now! It was a friends idea so I can't take credit for that one. The troubleshooting page I had did not have a test for the 5 volts but I did everything else. I also would get some inconsistant results which helped lead to the ECM Always something interesting!
CU around Sac, Bob
No I did not buy the book. I had a friend a "Corvette Care" in Rancho Cordova photocopy me one page of troubleshooting. Got the problem solved now. If you tapped on the ECM everything cured itself! Bad ECM. All OK now! It was a friends idea so I can't take credit for that one. The troubleshooting page I had did not have a test for the 5 volts but I did everything else. I also would get some inconsistant results which helped lead to the ECM Always something interesting!
CU around Sac, Bob
