Help: CCM code H72 please
Drifting
Joined: Mar 2000
Posts: 1,630
Likes: 1
From: Woodstock GA
Re: Help: CCM code H72 please (Vette73)
If you have an after market radio this bulletin may apply, if not have you removed the radio or A/C control head and maybe turned the key on, it's a code for LCD dimming output circuit with either an open or short to groung and it can set very fast a very slight loose connection of one of the terminals can set this code, if you do not have problems with the LCD in the radio or A/C control head don't worry about it if you have one of those intermitten strange behavior A/C control heads that could be the cause but I wouldn't loose any sleep over it.
David Fulcher
CAUSE:
----- With an aftermarket radio installed, DTC's 72 and 74 are likely to be set because the LCD and LED dimming lines to the radio have gone to an open circuit, because these inputs do not exist in an aftermarket radio.
CORRECTION:
---------- 1. Disconnect negative battery cable.
2. Remove the radio control head, following the directions in the Service Manual, Section 8C. This will allow access to the radio control head wiring.
3. Add 1 K ohm, 1/2 watt resistors as shown in the illustration. The resistors are available from a local electronics supply store, such as *Radio Shack. The resistors should be connected to a 12 volt ignition- switched circuit. For 1991 to 1993, there is an auxiliary power pickup in the console. For 1990, ignition circuit number 300 should be used. See Section 8A for wiring details.
4. Reinstall the radio, then reconnect negative battery cable. Clear the CCM DTC's as shown in Section 8D, and verify proper operation.
David Fulcher
CAUSE:
----- With an aftermarket radio installed, DTC's 72 and 74 are likely to be set because the LCD and LED dimming lines to the radio have gone to an open circuit, because these inputs do not exist in an aftermarket radio.
CORRECTION:
---------- 1. Disconnect negative battery cable.
2. Remove the radio control head, following the directions in the Service Manual, Section 8C. This will allow access to the radio control head wiring.
3. Add 1 K ohm, 1/2 watt resistors as shown in the illustration. The resistors are available from a local electronics supply store, such as *Radio Shack. The resistors should be connected to a 12 volt ignition- switched circuit. For 1991 to 1993, there is an auxiliary power pickup in the console. For 1990, ignition circuit number 300 should be used. See Section 8A for wiring details.
4. Reinstall the radio, then reconnect negative battery cable. Clear the CCM DTC's as shown in Section 8D, and verify proper operation.
Thread Starter
LS/MFT
Joined: Jun 2000
Posts: 5,874
Likes: 0
From: Cary IL
St. Jude Donor '09-'10-'11-'12
Re: Help: CCM code H72 please (David-F)
David,
Thanks for the help. Must be one of those strange anomolies, as I have the factory Bose and neither it nor the ECC has ever been out (under my watch). I cleared the code; hopefully it's gone forever.
Thanks for the help. Must be one of those strange anomolies, as I have the factory Bose and neither it nor the ECC has ever been out (under my watch). I cleared the code; hopefully it's gone forever.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
