94 LT1 Code H27 in module 4 help
Thread Starter
Instructor
Joined: Apr 2009
Posts: 115
Likes: 0
From: Rising Sun Md.
94 LT1 Code H27 in module 4 help
Trying to clear this bugger H27 but no clue where to start..I was told the H says it was in the history so its just an old stored code..and that it refers to a Quad Driver #2 voltage issue...I removed power over night and with 15 miles or so it returns....I really need to be pointed at where to find the error because times are tough and I cant afford GMs techs to be allowedto pick my pockets...HeLP!!!
Race Director
Joined: Mar 2015
Posts: 15,926
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Short either pin 4 or 5 to pin 12.
Turn ignition to run (don't start the engine).
|01|02|03|04|05|06|07|08|
|09|10|11|12|13|14|15|16|
Look at the cluster LCD it will cycle thru the modules
and display any error codes for that module.
Module 1 is the CCM (Central Control Module)
Module 4 PCM/ECM (Engine Computer)
Module 9 ABS (Anti Lock Brake)
Module A DERM (Air Bag System)
After the error codes are displayed, you'll see 1.0
in the LCD which indicates the system is waiting for further instructions.
To Clear any codes for the CCM
Press the Trip/Odo until you see 1.7
Press Eng/Met button and hold until ____ appears.
To clear any codes for the other modules.
Press the Trip Reset button until the desired module is displayed.
1.0 CCM
4.0 ECM
9.0 ABS
A.0 Derm
Then Press the Trip/Odo button until you see
For CCM 1.7
For ECM 4.7
For ABS 9.7
For DERM A.7
To clear any codes for that module Press Eng/Met and hold until ____ appears.
Turn ignition off and back on and verify the error codes are cleared.
C12 is not an error code but indicates the On board diagnostics are operational.
Found this
Turn ignition to run (don't start the engine).
|01|02|03|04|05|06|07|08|
|09|10|11|12|13|14|15|16|
Look at the cluster LCD it will cycle thru the modules
and display any error codes for that module.
Module 1 is the CCM (Central Control Module)
Module 4 PCM/ECM (Engine Computer)
Module 9 ABS (Anti Lock Brake)
Module A DERM (Air Bag System)
After the error codes are displayed, you'll see 1.0
in the LCD which indicates the system is waiting for further instructions.
To Clear any codes for the CCM
Press the Trip/Odo until you see 1.7
Press Eng/Met button and hold until ____ appears.
To clear any codes for the other modules.
Press the Trip Reset button until the desired module is displayed.
1.0 CCM
4.0 ECM
9.0 ABS
A.0 Derm
Then Press the Trip/Odo button until you see
For CCM 1.7
For ECM 4.7
For ABS 9.7
For DERM A.7
To clear any codes for that module Press Eng/Met and hold until ____ appears.
Turn ignition off and back on and verify the error codes are cleared.
C12 is not an error code but indicates the On board diagnostics are operational.
Found this
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Trying to clear this bugger H27 but no clue where to start..I was told the H says it was in the history so its just an old stored code..and that it refers to a Quad Driver #2 voltage issue...I removed power over night and with 15 miles or so it returns....I really need to be pointed at where to find the error because times are tough and I cant afford GMs techs to be allowedto pick my pockets...HeLP!!!
You mention '94 and you mention H27 BUT you mention "quad-driver" - I suggest you back up if this car is a '94 and see what the actual fault code 27 is. It ain't "quad-driver". I'll bet.
Set about doing the diagnostics for the DTC and then come back with questions.
If it's really NOT a '94 then correct the year !! You can't change the original title but you might confirm in the next post.
Last edited by WVZR-1; Aug 29, 2015 at 12:25 PM.
Thread Starter
Instructor
Joined: Apr 2009
Posts: 115
Likes: 0
From: Rising Sun Md.
Thanks guys....I went through and cleared all faults and the H27 and H41 are what seem to reoccur after the clear sequence and the Service engine light pops back up...I did see the EGR solenoid and am ordering a new one but will need to do research on how to deal with the H41..any info to point me in the right direction would be greatly appreciated...you guys are all awesome
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
DTC 41 relates to the drive signal from the PCM to the ICM and will not turn on the MIL lamp. It can also disable the injectors. I would get your code 27 repaired first by replacing the EGR solenoid.
Then check your codes again. There is a possibility the ICM might have to be replaced to get rid of the 41 code. I wouldn't think the PCM would really be an option at this point to be replaced. Other than that I would clean up the connectors for that pin and inspect them. Basically the PCM thinks the signal is above 4.6 ac volts. It's the white wire, pin B on the ICM
Then check your codes again. There is a possibility the ICM might have to be replaced to get rid of the 41 code. I wouldn't think the PCM would really be an option at this point to be replaced. Other than that I would clean up the connectors for that pin and inspect them. Basically the PCM thinks the signal is above 4.6 ac volts. It's the white wire, pin B on the ICM
