Code pulled: C72 H72
Thread Starter
Racer
Joined: Oct 2006
Posts: 403
Likes: 1
From: Merritt Island Florida
Code pulled: C72 "LCD DIMMING OPEN" What does this mean???
Can someone look up in their manual and tell me what does "LCD Dimming Open" means? 
Can I fix this myself? I'm at the level of 'Moron Mechanic' so it doesn't take much to overwhelm me.
Any help/advice is appreciated...
Billy
Can I fix this myself? I'm at the level of 'Moron Mechanic' so it doesn't take much to overwhelm me.
Any help/advice is appreciated...
Billy
Last edited by wilsonbh; Dec 18, 2006 at 04:12 AM. Reason: More data determined...
Thread Starter
Racer
Joined: Oct 2006
Posts: 403
Likes: 1
From: Merritt Island Florida
no, stock radio setup....l s
All stock....
My car gives me a C72 in module 1.0. Was hoping someone could look that up in the service manual and tell me what it says to do. I don't have a service manual.
Billy
Last edited by wilsonbh; Dec 18, 2006 at 04:04 AM. Reason: Still learning about the problem...
Thread Starter
Racer
Joined: Oct 2006
Posts: 403
Likes: 1
From: Merritt Island Florida
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Ok, what else doesnt work?? I havent had a chance to look in my 94 service manual yet. The horn could either be a fuse or the clock spring. Check and see if the horn works by setting off the alarm, if it does work, but wont work when you press the buttons on the steering wheel, its probably the clock spring. If it doesnt work with the alarm set off, it could be a fuse, amonst other things...
Last edited by Casethecorvetteman; Dec 18, 2006 at 01:39 PM.
Thread Starter
Racer
Joined: Oct 2006
Posts: 403
Likes: 1
From: Merritt Island Florida
Ok, what else doesnt work?? I havent had a chance to look in my 94 service manual yet. The horn could either be a fuse or the clock spring. Check and see if the horn works by setting off the alarm, if it does work, but wont work when you press the buttons on the steering wheel, its probably the clock spring. If it doesnt work with the alarm set off, it could be a fuse, amonst other things...
Billy
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Does the horn work when the alarm goes off or not? Lock the doors with the electric locking switch on the door, shut the doors, wait til the security light has gone out, then reach in the window you left open and unlock the door, when you open it the alarm should be set off. The horn should blow. Does it do this?
Follow the procedure below and see what the PKE system is doing and see if its working or not:
To run a diagnostic on the PKE system, connect pins 4 and 8 on the ALDL (see pic below to see pin label order)
And the PKE diagnostic system works as follows:
With pins 4 and 8 connected, the PKE light in the Driver Info Centre will flash the codes.
Here is the list of DTCs and what they mean:
DTC #12: Receiver Memory Bad
DTC #13: Transmitter Not in Range
DTC #14: Non-Valid Transmitter Received
DTC #15: Valid Transmitter Received
DTC #16: Passenger Door Button Depressed
DTC #17: Hatch Button Depressed
Then check your way through all of these items below
Check the + connection at the alternator
Check and clean BOTH battery terminals
If the battery has been flat a few times get rid of it and put a new one in there
Check all the fuses and make certain they are all in nice and tight
Check all the grounds and make sure they are clean and tight
Ill look at the service manual soon and see what i can see, i havent had a chance to get to it yet. My car is also a 94 so i have the correct GM service manual.
Follow the procedure below and see what the PKE system is doing and see if its working or not:
To run a diagnostic on the PKE system, connect pins 4 and 8 on the ALDL (see pic below to see pin label order)
And the PKE diagnostic system works as follows:
With pins 4 and 8 connected, the PKE light in the Driver Info Centre will flash the codes.
Here is the list of DTCs and what they mean:
DTC #12: Receiver Memory Bad
DTC #13: Transmitter Not in Range
DTC #14: Non-Valid Transmitter Received
DTC #15: Valid Transmitter Received
DTC #16: Passenger Door Button Depressed
DTC #17: Hatch Button Depressed
Then check your way through all of these items below
Check the + connection at the alternator
Check and clean BOTH battery terminals
If the battery has been flat a few times get rid of it and put a new one in there
Check all the fuses and make certain they are all in nice and tight
Check all the grounds and make sure they are clean and tight
Ill look at the service manual soon and see what i can see, i havent had a chance to get to it yet. My car is also a 94 so i have the correct GM service manual.
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Thread Starter
Racer
Joined: Oct 2006
Posts: 403
Likes: 1
From: Merritt Island Florida
Ok, what else doesnt work?? I havent had a chance to look in my 94 service manual yet. The horn could either be a fuse or the clock spring. Check and see if the horn works by setting off the alarm, if it does work, but wont work when you press the buttons on the steering wheel, its probably the clock spring. If it doesnt work with the alarm set off, it could be a fuse, amonst other things...
Another data point, the radio does not work as it's supposed to. The CD mechanism is boogered up and will not eject a disc. I plan to pull it out and send it to Doctor Don soon.
The biggest aggravation though is this fob not being available. Would be great to have this feature. Can't tell you how many times I've needed the hatch to open for things but had to crawl inside the car to push the button. Would have been great to use the fob for that.
I tried the 4 and 8 pins but don't get a reaction on the display. The 4 and 12 pin shorted give me the C72 reading.
I'll keep trouble shooting it and maybe in time, I'll stumble on the solution. Your help is appreciated . . .
Billy
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
You wont see anything on the digital display with 4 and 8 joined, the PKE diagnostic should make the "Passive Keyless Entry" light flash on the DIC to indicate the codes.
If you havent done so, clear the H72, then see if it comes back, and if it does, try to remember as much as you can about the situation. (temps/speeds/gear/head lights on or off/radio on or off/A/C on or off/ length of time the car had been running, etc)
Hope youre having a great Christmas day mate
If you havent done so, clear the H72, then see if it comes back, and if it does, try to remember as much as you can about the situation. (temps/speeds/gear/head lights on or off/radio on or off/A/C on or off/ length of time the car had been running, etc)
Hope youre having a great Christmas day mate
Thread Starter
Racer
Joined: Oct 2006
Posts: 403
Likes: 1
From: Merritt Island Florida
Electrical Problems
Here is the next bit of data learned. The fuse for the horn immediately blows and the horn sounds for a second as it blows. So anyone have any idea what is wrong along this line of detail? Could the horn relay be stuck in open?
I still get a C72 error code reading. Maybe it's related to the horn problem?
The car runs great, just no horn, no fob operation.
Is it dealership time?
Billy
I still get a C72 error code reading. Maybe it's related to the horn problem?
The car runs great, just no horn, no fob operation.
Is it dealership time?
Billy
Thread Starter
Racer
Joined: Oct 2006
Posts: 403
Likes: 1
From: Merritt Island Florida
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Possibly, but id say unlikely. unplug them 1 at a time and see if one or the other will work on its own. Highly bloody unlikely both would be faulty.
Have you ordered a GM shop manual set for it yet? Would be a very good investment at this point in time.
If it is blowing a fuse, its either drawing more current than the fuse can allow, or its shorting out, which is causing the circuit to draw more current than the fuse can allow. Either way, its blowing the fuse, and that is a wiring issue somewhere, and they fact it blows the fuse when you blow the horn indicates very strongly that it would be related to the horn.
Have you ordered a GM shop manual set for it yet? Would be a very good investment at this point in time.
If it is blowing a fuse, its either drawing more current than the fuse can allow, or its shorting out, which is causing the circuit to draw more current than the fuse can allow. Either way, its blowing the fuse, and that is a wiring issue somewhere, and they fact it blows the fuse when you blow the horn indicates very strongly that it would be related to the horn.
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Can't tell you how many times I've needed the hatch to open for things but had to crawl inside the car to push the button. Would have been great to use the fob for that.
Both my C4's have a switch on the DRIVERS door that operates the rear window solenoid.
Don't know if your 94 does or not but I thought it was a standard 'feature'.
Look on the door facew when the door is open by the door seal for a black switch that you can push to open the rear window.
Good luck with the rest of your trouble shooting.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Yeah Jim they do mate, mine has one on each door cause its been converted to right hand drive. Im not sure what year they went back to only being on the driver door but my 87 had one on each door as well even when it was factory perfect.
Thread Starter
Racer
Joined: Oct 2006
Posts: 403
Likes: 1
From: Merritt Island Florida
My car has a new battery but still get the SYS light. Other issues it has is it blows any fuse put into the horn slot of the fuse box. Thinking it may have something to do with the SYS? Just not sure. Also, it won't program in a fob. Additionally, the stock bose radio is messed up. Won't eject a CD but does play nicely, both the CD in it and the radio. I plan to remove it and send it to Dr Don for refurbishment, as soon as I get the guts up to dig it out of the dash.
I love the car. It's great fun to drive. Just trying to get it to perfection with these electrical issues. Haven't tried troubleshooting the horn yet but do plan to do so this weekend.
Billy
