Code Help h51 h72 h74 h23 h83
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From: Los Angeles
Code Help h51 h72 h74 h23 h83
Module 1 (CCM) - H51 H72 H74
Module 4 (ECM) - H23 H83
Module 9 - no codes
1993 corvette LT1 (stroked 383 stroker, 400 crank, lt4 hot cam, 1.6 roller rockers)
(1) My aftermarket head unit is not turning on which I believe is code 72 but not sure. (2) My windows are not working on both sides will not function (3) The radio is out in the car however I'm getting power so I'm assuming its a dead aftermarket head unit which fried when I jumped the car when the distributor needed to be replaced along with the battery (4) Something is blowing my headlight switch which I believe is due to some short in the tail lights causing the headlight switch dimmer lever to freeze and the headlight switch to go faulty.
Any help appreciated on these codes, what they mean and how to remove them. Thanks
Module 4 (ECM) - H23 H83
Module 9 - no codes
1993 corvette LT1 (stroked 383 stroker, 400 crank, lt4 hot cam, 1.6 roller rockers)
(1) My aftermarket head unit is not turning on which I believe is code 72 but not sure. (2) My windows are not working on both sides will not function (3) The radio is out in the car however I'm getting power so I'm assuming its a dead aftermarket head unit which fried when I jumped the car when the distributor needed to be replaced along with the battery (4) Something is blowing my headlight switch which I believe is due to some short in the tail lights causing the headlight switch dimmer lever to freeze and the headlight switch to go faulty.
Any help appreciated on these codes, what they mean and how to remove them. Thanks
Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
CCM 51 - pass key incorrect key resistance could indicate key or cylinder on its way out.
72 and 74 related to OEM radio missing doesn't hurt anything makes "sys" flash
ECM 23 IAT sensor
83 doesn't apply to a 93. It's a transmission code for 4l60e not used in Corvette until 94. I would check IAT clear codes and recheck DTCs
72 and 74 related to OEM radio missing doesn't hurt anything makes "sys" flash
ECM 23 IAT sensor
83 doesn't apply to a 93. It's a transmission code for 4l60e not used in Corvette until 94. I would check IAT clear codes and recheck DTCs
Thread Starter
Intermediate
Joined: Sep 2015
Posts: 43
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From: Los Angeles
Kevova,
Thanks for the response. I tried replacing the aftermarket radio today with a new one unfortunately that radio would not turn on either. Replaced the window switch and that did not work noticed I'm not getting power to any of the wires. I am getting power to the head unit which is weird maybe another wire needed isn't getting power. I just borrowed a 91 shop manual from a friend. My alternator recently broke by getting extremely hot and smoking which i replaced no problems.
The key has a bypass on it. 72 & 74 shouldn't show if the radio is connected right?
ECM 23 IAT sensor what is that?
I'll clear the codes and check tomorrow.
Thanks for the response. I tried replacing the aftermarket radio today with a new one unfortunately that radio would not turn on either. Replaced the window switch and that did not work noticed I'm not getting power to any of the wires. I am getting power to the head unit which is weird maybe another wire needed isn't getting power. I just borrowed a 91 shop manual from a friend. My alternator recently broke by getting extremely hot and smoking which i replaced no problems.
The key has a bypass on it. 72 & 74 shouldn't show if the radio is connected right?
ECM 23 IAT sensor what is that?
I'll clear the codes and check tomorrow.
Thread Starter
Intermediate
Joined: Sep 2015
Posts: 43
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From: Los Angeles
Also the ASR switch on the headlight switch won't work to turn it off. When i punch the gas the brake light comes on and I can feel it slow the car down. This car has been one thing after another causing me headaches hopefully you can help direct me on what to do.
Thread Starter
Intermediate
Joined: Sep 2015
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From: Los Angeles
The orange wire going to the going to the stereo should have volts when the key is turned on.... For some reason this wire is not getting power which i believe is the problem to why the head unit will not turn on. Does anyone have a wire diagram for this and any suggestions on how to diagnose this issue? Thanks
Le Mans Master
Joined: Sep 2013
Posts: 6,192
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From: near the thumb in the mitten
IAT is the Intake Air Temperature sensor located on intake duct.
If you want to DIY get factory service manuals (2 books) ebay or c4 parts wanted/for sale forum.
A resistor can be installed to trick CCM and prevent the 2 codes. There is a technical service bulletin discribing correction, which I have misplaced.
Car uses component radio. Head in dash, reciever under liner in rear storage well, and if Bose amps made to speakers. To try to make factory radio work, you need to know which one you have. Under console lid there is a decal with 3 digit codes( rpo) VIN is on it. Make sure VIN matches VIN on dash, radio is a U__ code and will indicate what supposed to be installed.
If you want to DIY get factory service manuals (2 books) ebay or c4 parts wanted/for sale forum.
A resistor can be installed to trick CCM and prevent the 2 codes. There is a technical service bulletin discribing correction, which I have misplaced.
Car uses component radio. Head in dash, reciever under liner in rear storage well, and if Bose amps made to speakers. To try to make factory radio work, you need to know which one you have. Under console lid there is a decal with 3 digit codes( rpo) VIN is on it. Make sure VIN matches VIN on dash, radio is a U__ code and will indicate what supposed to be installed.
Thread Starter
Intermediate
Joined: Sep 2015
Posts: 43
Likes: 0
From: Los Angeles
Turned out the stereo and window issue was a relay missing under the dash. The main issue now is diagnosing the electrical issue with the headlight switch, I keep blowing them, when i replace with a new one it works intermediately all lights has to be a short right? do you have any diagrams I have a 91 server manual but its hard to know where those wires go.
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Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
Explain blowing headlight switch. Switch has circuit breaker built to it which should reset. Stock headlight bulbs or aftermarket " super bright" system. I would unplug headlights. Then check for voltage at headlights with switch on.