H codes
Thread Starter
Cruising
Joined: Nov 2020
Posts: 14
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H codes
I understand that h codes mean they were a problem, but are currently not one right now. My car is throwing an H48 in module 4, H72 in module 9, and an H24 in module A. I just got the service manual today, but I see two things for DTC 24 which are for the courtesy lamp but also the vehicle speed sensor and am a little confused. Additionally, I am curious because they are all h codes, do h codes trigger a check engine light? I am looking at the H48 and H72 codes in the service manual and am curious about how to decipher between modules 1,4,9, and A. Any help is greatly appreciated.
My car- 1994 c4 corvette base model coupe with a 6-speed manual. The only thing I have done is replace the EGR solenoid to fix a check engine light prior, I installed led lights in the car (maybe why it is an h24, but they are no polarity so should be good ) and then I installed a new ignition cylinder because the old one was broken, replaced the fuel pump, and the rest were all irrelevant.
My car- 1994 c4 corvette base model coupe with a 6-speed manual. The only thing I have done is replace the EGR solenoid to fix a check engine light prior, I installed led lights in the car (maybe why it is an h24, but they are no polarity so should be good ) and then I installed a new ignition cylinder because the old one was broken, replaced the fuel pump, and the rest were all irrelevant.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
H means history and not present fault falls under intermittent
C means current so fault it present and should be able to accurately diagnosed.
Some codes will only set or be current with engine running.
C means current so fault it present and should be able to accurately diagnosed.
Some codes will only set or be current with engine running.
Thread Starter
Cruising
Joined: Nov 2020
Posts: 14
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the air bags were removed on the vehicle before i bought it, but i wired a resister to the clock spring to remove the air bag light.
I open the diagnostic mode, review codes, clear codes, take out paper clip, start the car, check engine light comes back on, those h codes come back on when i go back into diagnostic mode.
I open the diagnostic mode, review codes, clear codes, take out paper clip, start the car, check engine light comes back on, those h codes come back on when i go back into diagnostic mode.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
For a 1994, if you have a laptop, your best bet to do current codes and datalogging is this cable: http://aldlcable.com/products/aldlobd2u.asp
And this free software: http://fbodytech.com/eehack-2/download-eehack/
As to your codes, here is what they mean:
Module 4 (Engine/Transmission) H48: MAF Sensor Circuit Error (car switches to Speed Density mode when this DTC is set; should not significantly impact operation)
Module 9 (ABS/ASR) H72: Serial Data Fail (this can be ignored; it’s likely a result of your diagnostic efforts and is not a real problem, feel free to reset it)
Module A (Airbag) H24: Initiator Circuit Voltage Low
If you do not have a Factory Service Manual, buy one. They are about $30 on RockAuto (look at the bottom of the “literature” section).
And this free software: http://fbodytech.com/eehack-2/download-eehack/
As to your codes, here is what they mean:
Module 4 (Engine/Transmission) H48: MAF Sensor Circuit Error (car switches to Speed Density mode when this DTC is set; should not significantly impact operation)
Module 9 (ABS/ASR) H72: Serial Data Fail (this can be ignored; it’s likely a result of your diagnostic efforts and is not a real problem, feel free to reset it)
Module A (Airbag) H24: Initiator Circuit Voltage Low
If you do not have a Factory Service Manual, buy one. They are about $30 on RockAuto (look at the bottom of the “literature” section).
Last edited by Nomake Wan; Mar 22, 2021 at 09:22 PM.
Thread Starter
Cruising
Joined: Nov 2020
Posts: 14
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Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
Would this work instead: https://www.ebay.com/itm/13320491757...BoC1c4QAvD_BwE
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Thread Starter
Cruising
Joined: Nov 2020
Posts: 14
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There are airbags in the passenger seat, just not the driver seat because the steering wheel is an aftermarket one. And the car runs perfectly fine, it is just shooting codes that I think are not a part of the engine itself.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
You have to clear the codes in each module when the 'paperclip' is shorting the CCM diagnostic enable port to ground. (I don't know the pin numbers for the 95's port. Don't care to look them up). If you have codes in 3 modules, you have to clear in 4.9, 9.9, and A.9.
If you don't have airbags, why not remove (or just disconnect) the DERM and jumper the correct 2 cavities in the connector so the engine still runs? (I'm not going to tell which 2 it is. Liability chit....).
If you don't have airbags, why not remove (or just disconnect) the DERM and jumper the correct 2 cavities in the connector so the engine still runs? (I'm not going to tell which 2 it is. Liability chit....).
OP already knows which pins since he already knows how to enter diagnostic mode, but for reference it is 4 and 12.
Team Owner
Joined: Sep 2003
Posts: 25,348
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i edited the post a-hole. In your HASTE to copy my post, nowYOU HAVE MADE AN ERROR. Please extend the courtesy of fixing your post pointing out the error that i corrected within about 2 minutes. Look at the difference between the post time and the edit time.
Q U I T C O P Y I N G M Y P O S T S.
Q U I T C O P Y I N G M Y P O S T S.
OP for a late C4 @Nomake Wan is pretty damn reliable and responsive. A week ago I actually believe I suggested a 'house-call'. since you/he are 'left coast' neighbors. You've got the FSM now so spend some time acquainting yourself with it.
Is your FSM paper or .pdf?
Last edited by WVZR-1; Mar 23, 2021 at 08:03 AM.