1992 Diagnostics
Thread Starter
4th Gear
Joined: May 2023
Posts: 4
Likes: 0
1992 Diagnostics
Hello all, today I was trying to diagnose a no start issue so I pulled the codes from the car to see if it could give me any extra information. I pulled an H51 code and a H72 code. I read online that H51 could either be “invalid key detection” or a “PROM/EPROM error” and that the H72 code can have something to do with the radio or dimmer circuit, (which has the stock unit) or the “Gear Selector Switch Fault (Start Lockout). I am wondering if anyone can give me insight into what code means what since I’m finding numerous things everywhere. My car is a 1992 by the way.
The car starts intermittently and the dash, flashing security light, and courtesy lights don’t come on but when the do come on the car starts up fine.
The car starts intermittently and the dash, flashing security light, and courtesy lights don’t come on but when the do come on the car starts up fine.
Melting Slicks
Joined: May 2003
Posts: 2,076
Likes: 281
From: Dyersburg TN
Have you had a new key made or any damage to your old key? Do you have more than one ignition key? Would be interesting to know if this is key related or all keys (CCM). Our local locksmith has a reader that will give the code from the resistor in key. You could do that to check if all your keys have same code.
The other code does sound like a bad ground. Ground wires are the gremlins of the C4 cars.
The other code does sound like a bad ground. Ground wires are the gremlins of the C4 cars.
