INFL REST repair complete need help reset
07-22-2009, 10:04 PM
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4th Gear
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INFL REST repair complete need help reset
First off thanks to everyone for their help, especially PIPE, DADs90 and Bad Karma. I followed the procedure for cleaning the air bag sensors and now I need assistance with the procedure for resetting the INFL REST warning light.
07-25-2009, 09:17 AM
#4
Melting Slicks
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I have e files for 3 procedures. I did not save the links however here is the text of all 3 one post at a time.
How to correctly and inexpensively correct the 'Inf Rest' light on 1990 Corvettes.
The 90 is infamous for this light staying on. It seems that there are two sensors, one on the frame underneath the battery box, and one underneath the windshield washer container. Both bolt directly to the frame. These little electronic wizards detect a crash via vibration in the frame, and then set off the air bag.
The problem is two fold. First, their location promotes getting water on them. Secondly, the water causes a corrosion problem between the sensor and the frame. These little wizards are so sensitive to corrosion, 1/2 of one ohm of resistance that developes between it and the frame will send a fault light code to the computer, and trigger the trouble light. Most of the time, the air bags are still functional, just the light is on.
But, on to fixing the problem...
First, let's check the codes in your computer to make sure this is the problem. Using a long jumper wire, jumper pin # K on the computer link connector to ground, like the seat frame. Pin K is the fouth slot from the left on the bottom row, or third from the right. (The connector is under the drivers side dash). Turn on the ignition, but don't start the car. Via flashing engine light, you will be able to read the codes in your computer. It will first flash a code 12 three times. The light will flash like morse code, a long lit bulb, followed by two short lit bulbs will be a 12. Once the three code 12's flash, then you will have another code, likely it will be a 25 or 26, but could also be a 15 or 16. ( , Mine (Jay) was a code 16, Indicating right side sensor) If it is not one of these, you have a different problem, so let me know if your's is not one of these. Code 26 is most common, right front sensor fault.
Assuming you have a 15, 16, 25, 26 code, you will be following the service bulletin #90-436-9J. To fix, you have to unhook the battery. Next, remove the side panel and inner fender well cover from the front tires. (Note, I also had to remove the tire to get to the bottom 2 torx screws) Then you can unbolt the sensors. Next sand the frame and back of the sensors with sandpaper, and then install di-electric grease (I found permatex tune-up,
di-elecrical grease at Pep Boys) on the back of the sensor, then re-install it. After this is done, you can then reset the computer. Now this is where the dealers have all of the problems. Since it is very difficult to reset, they usually replace the sensors with new ones, so they dont have to go through this. But if you can accomplish this, it will save you bunches of green paper!!!
Taking a jumper wire hooked to terminal K, ground it to the seat frame, and count one thousand one. one thousand two, one thousand three. Then unhook it from ground, count one thousand one, one thousand two, one thousand three. Then reground it once more, and count one thousand one, one thousand two, one thousand three. The code will disappear, leaving only a code 12 if you are successful. If not, retry it again and again. A friend of mine did it 10 times before it was successful. But, think of the money you would have to pay a mechanic to do THIS!!!
( , this is where I had the most trouble, until I got an email from Dan's friend and late-model guru, Ed.
Here is the secret....With the ignition off. Place the jumper wire in the K terminal and ground it to the seat frame...Switch the ignition on and AS SOON as the light begins to flash, remove the jumper from the frame and count 1001,1002,1003, Then reground it and hopefully you will only see code 12's flashing. I spent an hour yesterday doing it wrong and tonight I got it the first try using Ed's method. Anyway, on with Dan's instructions) The A/C condensor is what drops water on this sensor, and causes the problem.
In 91 they used di-electric grease, and the problem was fixed. As a precautionary note, do not use a volt ohm meter to do any troubleshooting with this system. The battery in the ohm meter will set off the air bag system. This is how mechanics get really in deep s@#* with their boss! As long as you can refrain from using a meter, you will be ok.
--------------------------------------------------------------------------------
How to correctly and inexpensively correct the 'Inf Rest' light on 1990 Corvettes.
The 90 is infamous for this light staying on. It seems that there are two sensors, one on the frame underneath the battery box, and one underneath the windshield washer container. Both bolt directly to the frame. These little electronic wizards detect a crash via vibration in the frame, and then set off the air bag.
The problem is two fold. First, their location promotes getting water on them. Secondly, the water causes a corrosion problem between the sensor and the frame. These little wizards are so sensitive to corrosion, 1/2 of one ohm of resistance that developes between it and the frame will send a fault light code to the computer, and trigger the trouble light. Most of the time, the air bags are still functional, just the light is on.
But, on to fixing the problem...
First, let's check the codes in your computer to make sure this is the problem. Using a long jumper wire, jumper pin # K on the computer link connector to ground, like the seat frame. Pin K is the fouth slot from the left on the bottom row, or third from the right. (The connector is under the drivers side dash). Turn on the ignition, but don't start the car. Via flashing engine light, you will be able to read the codes in your computer. It will first flash a code 12 three times. The light will flash like morse code, a long lit bulb, followed by two short lit bulbs will be a 12. Once the three code 12's flash, then you will have another code, likely it will be a 25 or 26, but could also be a 15 or 16. ( , Mine (Jay) was a code 16, Indicating right side sensor) If it is not one of these, you have a different problem, so let me know if your's is not one of these. Code 26 is most common, right front sensor fault.
Assuming you have a 15, 16, 25, 26 code, you will be following the service bulletin #90-436-9J. To fix, you have to unhook the battery. Next, remove the side panel and inner fender well cover from the front tires. (Note, I also had to remove the tire to get to the bottom 2 torx screws) Then you can unbolt the sensors. Next sand the frame and back of the sensors with sandpaper, and then install di-electric grease (I found permatex tune-up,
di-elecrical grease at Pep Boys) on the back of the sensor, then re-install it. After this is done, you can then reset the computer. Now this is where the dealers have all of the problems. Since it is very difficult to reset, they usually replace the sensors with new ones, so they dont have to go through this. But if you can accomplish this, it will save you bunches of green paper!!!
Taking a jumper wire hooked to terminal K, ground it to the seat frame, and count one thousand one. one thousand two, one thousand three. Then unhook it from ground, count one thousand one, one thousand two, one thousand three. Then reground it once more, and count one thousand one, one thousand two, one thousand three. The code will disappear, leaving only a code 12 if you are successful. If not, retry it again and again. A friend of mine did it 10 times before it was successful. But, think of the money you would have to pay a mechanic to do THIS!!!
( , this is where I had the most trouble, until I got an email from Dan's friend and late-model guru, Ed. Here is the secret....With the ignition off. Place the jumper wire in the K terminal and ground it to the seat frame...Switch the ignition on and AS SOON as the light begins to flash, remove the jumper from the frame and count 1001,1002,1003, Then reground it and hopefully you will only see code 12's flashing. I spent an hour yesterday doing it wrong and tonight I got it the first try using Ed's method. Anyway, on with Dan's instructions) The A/C condensor is what drops water on this sensor, and causes the problem.
In 91 they used di-electric grease, and the problem was fixed. As a precautionary note, do not use a volt ohm meter to do any troubleshooting with this system. The battery in the ohm meter will set off the air bag system. This is how mechanics get really in deep s@#* with their boss!
As long as you can refrain from using a meter, you will be ok. --------------------------------------------------------------------------------
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RWR (07-05-2019)
07-25-2009, 09:19 AM
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Melting Slicks
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#2
O.K. Here is how I did it. I did the sanding thingy on my 90 coupe, with the battery disconnected and then went to clear the code by grounding K to the seat frame. I found it very hard to watch the codes on the dash and do the factory counting method. What I did was to make up two wires with alligator clips on both ends. One wire was hooked up to " K " and the other to the seat frame. Then I sat comfortably in the drivers seat and held both ends in my hands. As I watched the dash count off the three " 12,s " It was easy to touch the wires together when the " 16 " count started. I followed the factory count method and it was so easy the code was cleared the very first time. This worked for me. Allentown Ernie.
O.K. Here is how I did it. I did the sanding thingy on my 90 coupe, with the battery disconnected and then went to clear the code by grounding K to the seat frame. I found it very hard to watch the codes on the dash and do the factory counting method. What I did was to make up two wires with alligator clips on both ends. One wire was hooked up to " K " and the other to the seat frame. Then I sat comfortably in the drivers seat and held both ends in my hands. As I watched the dash count off the three " 12,s " It was easy to touch the wires together when the " 16 " count started. I followed the factory count method and it was so easy the code was cleared the very first time. This worked for me. Allentown Ernie.
07-25-2009, 09:20 AM
#6
Melting Slicks
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#3
How to Extinguish a '90 Seat Belt Light
--------------------------------------------------------------------------------
Sorry for the long post but I wanted to provide as much detail as possible in case others want to do what I've done.
+++++++
As pretty much everyone knows, the '90 Vette's INFL REST light will come on when one of the collision sensors out on the frame develops a bad ground--something that happens with virtually all '90 Vettes eventually. Many threads on this forum talk about how to deal with that problem and many folks fix the sensor problem but some don't. If you're one of those who has the problem but hasn't fixed it, you have an INFL REST light plus a Seat Belt light on all the time.
Unfortunately, my airbag module (DERM) bit the dust and GM doesn't sell them anymore so I was stuck with a INFL REST light and a seat belt light that were on all the time, and since it wasn't a bad sensor, it was unrepairable until I can find a working, used DERM (harder than it seems.)
So I disassembled the center of the instrument panel and placed a piece of black electrical tape on the back side of the DIC escutcheon which took care of the INFL REST light showing through but the seat belt light was still on.
I finally got tired of looking at it today and decided to see if there was an easy way to turn it off.
After disconnecting the battery and disabling the airbag, I looked at the seam where the transmission trim piece (the large carpeted panel that runs along the passenger side of the transmission tunnel) and the passenger side lower trim assembly come together.
When I pressed against the transmission trim piece at the seam, I noticed two yellow cables barely visible through the crack, one larger than the other.
The DERM is the only thing in the I.P center area that uses yellow insulation on the outside of cables so I knew they were from the DERM. The small diameter cable was the one that goes to the passenger side sensor out on the frame so I disregarded it and gently tugged on the bigger cable. Once I got a cable loop exposed, I took an exacto knife and VERY GENTLY made a small incision in the outer insulation so that I could see the wires inside. The FSM said that the wire going from the DERM to the CCM (that's what lights up the seat belt lamp when there is a S.I.R. problem) was black with a green stripe. I found that wire, pulled it through the cut in the insulation and snipped it. I positioned the cut ends of the black and green wire as far away from one another as possible, wound electrical tape around the insulation opening I'd made in the DERM cable (and also over the cut wire ends) and tie wrapped each end of the tape so it could not unwind. I stuffed the whole thing back into the crack, hooked the battery up and verified that the seat belt light only came on in response to the seat belt being unbuckled which it does.
So I now have a pre-90 'Vette as far as the air bag is concerned and there are no warning lights staring at me.
If I can ever find a working DERM, I've done nothing harmful because the wire I cut was on the defective DERM's cable which would be replaced anyway. Also, the cut wire was merely making a ground path for the CCM's seat belt lamp driver transistor so there is no voltage present on the cut wires and no hazard present due to the cut wire ends which are protected with electrical tape and tie wraps anyway.
Cautions:
Take the negative battery terminal loose and leave it loose for 15 minutes before you do this fix. (The DERM is "hot" for at least 10 minutes after you remove the voltage to it.)
You have to be very careful with the exacto knife. You don't want to cut any of the wires under the yellow insulation when you're opening it up so don't press hard on the knife when you're cutting the cable's insulation jacket.
Note that there is a solid green wire in the bundle. It's for use with a Tech 1 scan tool so don't cut that one by mistake. Only cut the black wire with the green stripe.
Place the ends of the cut wires away from one another and wind electrical tape around the whole area, tie wrapping the whole business at the ends where the tape wrap starts and stops.
How to Extinguish a '90 Seat Belt Light
--------------------------------------------------------------------------------
Sorry for the long post but I wanted to provide as much detail as possible in case others want to do what I've done.
+++++++
As pretty much everyone knows, the '90 Vette's INFL REST light will come on when one of the collision sensors out on the frame develops a bad ground--something that happens with virtually all '90 Vettes eventually. Many threads on this forum talk about how to deal with that problem and many folks fix the sensor problem but some don't. If you're one of those who has the problem but hasn't fixed it, you have an INFL REST light plus a Seat Belt light on all the time.
Unfortunately, my airbag module (DERM) bit the dust and GM doesn't sell them anymore so I was stuck with a INFL REST light and a seat belt light that were on all the time, and since it wasn't a bad sensor, it was unrepairable until I can find a working, used DERM (harder than it seems.)
So I disassembled the center of the instrument panel and placed a piece of black electrical tape on the back side of the DIC escutcheon which took care of the INFL REST light showing through but the seat belt light was still on.
I finally got tired of looking at it today and decided to see if there was an easy way to turn it off.
After disconnecting the battery and disabling the airbag, I looked at the seam where the transmission trim piece (the large carpeted panel that runs along the passenger side of the transmission tunnel) and the passenger side lower trim assembly come together.
When I pressed against the transmission trim piece at the seam, I noticed two yellow cables barely visible through the crack, one larger than the other.
The DERM is the only thing in the I.P center area that uses yellow insulation on the outside of cables so I knew they were from the DERM. The small diameter cable was the one that goes to the passenger side sensor out on the frame so I disregarded it and gently tugged on the bigger cable. Once I got a cable loop exposed, I took an exacto knife and VERY GENTLY made a small incision in the outer insulation so that I could see the wires inside. The FSM said that the wire going from the DERM to the CCM (that's what lights up the seat belt lamp when there is a S.I.R. problem) was black with a green stripe. I found that wire, pulled it through the cut in the insulation and snipped it. I positioned the cut ends of the black and green wire as far away from one another as possible, wound electrical tape around the insulation opening I'd made in the DERM cable (and also over the cut wire ends) and tie wrapped each end of the tape so it could not unwind. I stuffed the whole thing back into the crack, hooked the battery up and verified that the seat belt light only came on in response to the seat belt being unbuckled which it does.
So I now have a pre-90 'Vette as far as the air bag is concerned and there are no warning lights staring at me.
If I can ever find a working DERM, I've done nothing harmful because the wire I cut was on the defective DERM's cable which would be replaced anyway. Also, the cut wire was merely making a ground path for the CCM's seat belt lamp driver transistor so there is no voltage present on the cut wires and no hazard present due to the cut wire ends which are protected with electrical tape and tie wraps anyway.
Cautions:
Take the negative battery terminal loose and leave it loose for 15 minutes before you do this fix. (The DERM is "hot" for at least 10 minutes after you remove the voltage to it.)
You have to be very careful with the exacto knife. You don't want to cut any of the wires under the yellow insulation when you're opening it up so don't press hard on the knife when you're cutting the cable's insulation jacket.
Note that there is a solid green wire in the bundle. It's for use with a Tech 1 scan tool so don't cut that one by mistake. Only cut the black wire with the green stripe.
Place the ends of the cut wires away from one another and wind electrical tape around the whole area, tie wrapping the whole business at the ends where the tape wrap starts and stops.
07-25-2009, 10:56 AM
#7
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One thing that I found in my case....tried the connect--disconnect--3 sec. timing as soon as the code 12 started flashing...could not clear code. I then waited for the default code to start flashing after the code 12 was finished and it cleared the first time. Not saying it was the right procedure but it worked for me.
07-25-2009, 02:23 PM
#8
Drifting
I have the Button from Mid America it's nice not having to touch the ground wire to a seat frame or some piece of metal or wherever just hit the button and done. I'm glad ya got it fixed. It took a few times to clear even with the button. Glad I could put my 2 cents worth in there to help. Lots of people on here helped me out. Glad to help you. Pipe
07-05-2011, 12:17 PM
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Question for someone with knowledge please - On my 90 Coupe I cleaned and grounded the sensors, confirmed with ohm test. I'm still getting codes 16, 26, 42, 52 and 53. I've tried the re-setting methods as explained above (I hooked up a toggle switch between the K pin and A pin), practiced my timing, tried before the 12s and after the 12s when 16 started flashing, did it about 30 times each, no luck. I'm new to the car, but can tell from the body work that its been in at least one, maybe two crashes. I think I read in another forum that if the DERM has deployed in a crash event, that it has to be re-programmed at the factory or outside the car, that it can't be re=programmed or cleared through the ALDL. Can anyone advise if this is correct? Thanks.
