AC / Anti-lock brake light issue
- Thread starter CWARE
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Ok. I’ll try to get the code it’s throwing. I did try unplugging the ABS Controller for about a day or so and upon start up with everything still unplugged the ABS light wasn’t on. The AC still didn’t blow at all though. Still not sure if there is a connection between the two or not but it sure seems so.
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TheAutumnWind
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Doubt there is any connection
Did more troubleshooting on the Tahoe and still no luck. I checked the two ac related relays (under the hood and behind the dash) and both appeared to be good. I used a test light on the ac control module harness and it indicated there was power coming out of the harness into the module on the plug with 8 prongs. I’m assuming that’s how it should be.
I’m wondering now if there is a bag ground somewhere. I know it was stated that the ABS light and ac issue likely aren’t related but is there a possibility a ground somewhere is presenting the issue. Maybe a ground that grounds both the module and something ABS related? I’m not sure where else to go. I supposed I still need to attempt to get the OBD1 scanned for an exact abs Code.
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I’m wondering now if there is a bag ground somewhere. I know it was stated that the ABS light and ac issue likely aren’t related but is there a possibility a ground somewhere is presenting the issue. Maybe a ground that grounds both the module and something ABS related? I’m not sure where else to go. I supposed I still need to attempt to get the OBD1 scanned for an exact abs Code.
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TheAutumnWind
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Definitely should check your grounds. The one behind the block to the firewall often gets missed, and the one from the battery to the fender well area is just a sheetmetal screw and could come loose.
I checked the one from the battery to fender and it was fine. I located 2 on the firewall near the passenger side. One was up high and went into the harness for the underwood light. It was nice and tight and corrosion free. The one down lower underneath the area of the ac accumulator was removed and cleaned. The 3rd one was on the top of the passenger side frame section next to the motor. It appeared to have 2 ground straps connected to it. One went up to the ground mentioned earlier beneath the accumulator and the other went up into a harness that appeared to run up behind the motor. The ground point on the frame was extremely corroded. I took it all apartment and cleaned the screw and connections up. Put them back together and still nothing with the AC. The ground was getting a good connection as I tested it with a test light. The light came on when it hadn’t before.
Does anyone have a schematic showing all of the grounds on the vehicle?
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east302
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There is another ground (at least on the 96+) near the bottom of the harmonic balancer. I’d guess that the TBI had the same one.
On a 98, the ABS (different system I believe than the 95) and a/c panel look to share G105 which is the one by the harmonic balancer.
Back to the a/c controller, do the vent controls work (the air doors adjust)? Watch the one by the gas pedal since it’s easier to observe.
The blower has two wires connected to it. With fan selected on high, check for 12V at the blower wire using a chassis ground and then using the ground wire that connects to the blower.
Just for kicks, here are the diagnostics for an inoperable blower on a 98. Refer to wiring diagram above. The connector (or something at the panel) is different for a 95, but maybe it will help.
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On a 98, the ABS (different system I believe than the 95) and a/c panel look to share G105 which is the one by the harmonic balancer.
Back to the a/c controller, do the vent controls work (the air doors adjust)? Watch the one by the gas pedal since it’s easier to observe.
The blower has two wires connected to it. With fan selected on high, check for 12V at the blower wire using a chassis ground and then using the ground wire that connects to the blower.
Just for kicks, here are the diagnostics for an inoperable blower on a 98. Refer to wiring diagram above. The connector (or something at the panel) is different for a 95, but maybe it will help.
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Last edited:
There is another ground (at least on the 96+) near the bottom of the harmonic balancer. I’d guess that the TBI had the same one.
On a 98, the ABS (different system I believe than the 95) and a/c panel look to share G105 which is the one by the harmonic balancer.
Back to the a/c controller, do the vent controls work (the air doors adjust)? Watch the one by the gas pedal since it’s easier to observe.
The blower has two wires connected to it. With fan selected on high, check for 12V at the blower wire using a chassis ground and then using the ground wire that connects to the blower.
Just for kicks, here are the diagnostics for an inoperable blower on a 98. Refer to wiring diagram above. The connector (or something at the panel) is different for a 95, but maybe it will help.
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I looked for that ground near the balancer and did not locate one on my 95. I did locate the destination for one of the ground straps I mentioned before on the top of the passenger side frame rail next to the motor. It appears one of the straps goes to the back of the motor near the passenger side head/block. The bolt this strap is attached to is caked in oil but it seems almost impossible to reach on first glance. I’ll be attempting to deal with this now and see what happens.
I know that the blower motor works. I connected it to 12v and it fired right up. While the blower was running, I looked at the HVAC module but didn’t see any lights on indicating it was receiving power. Now the purple wire that I believe is the power wire that attaches to the blower does not seem to be supplying any power whatsoever to the blower. I tested it for 12v at the plug and got nothing and also tested it above the plug( into the wire itself) and got no power there either. I tracked that purple wire away from the blower motor and determined it ran to the plug for the blower relay. I previously tested the relay and it seemed to test good.
I then went through and re-checked the related fuses and all are still good.... This thing is wearing me out. I hate wiring which makes all of this extra brutal. Lol.
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east302
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The control panel supplies the relay (orange wire) in high and the resistor for other speeds. Do you have power upstream of the relay on the Orange or dark blue wires? Or any of the wires shown at connector C230?
Those wire colors are based on the 98 model diagram; I’d think it would be the same or pretty similar for a 95 but understand that there was something specific to the 95 that was not carried over to later models.
If you have power there, then the control panel blower switch should be fine (I would think). If no voltage there, then see if the control panel supply (brown wire, circuit 141 on diagram below) is getting power. It is grounded to G200, which is on the crossbar above your knee, roughly above the parking brake.
Is this a new panel? I had a Dorman one that started smoking within a few minutes of installation. If *nothing* works on the panel but you have power to it, then it may be a bum part.
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Those wire colors are based on the 98 model diagram; I’d think it would be the same or pretty similar for a 95 but understand that there was something specific to the 95 that was not carried over to later models.
If you have power there, then the control panel blower switch should be fine (I would think). If no voltage there, then see if the control panel supply (brown wire, circuit 141 on diagram below) is getting power. It is grounded to G200, which is on the crossbar above your knee, roughly above the parking brake.
Is this a new panel? I had a Dorman one that started smoking within a few minutes of installation. If *nothing* works on the panel but you have power to it, then it may be a bum part.
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The control panel supplies the relay (orange wire) in high and the resistor for other speeds. Do you have power upstream of the relay on the Orange or dark blue wires? Or any of the wires shown at connector C230?
Those wire colors are based on the 98 model diagram; I’d think it would be the same or pretty similar for a 95 but understand that there was something specific to the 95 that was not carried over to later models.
If you have power there, then the control panel blower switch should be fine (I would think). If no voltage there, then see if the control panel supply (brown wire, circuit 141 on diagram below) is getting power. It is grounded to G200, which is on the crossbar above your knee, roughly above the parking brake.
Is this a new panel? I had a Dorman one that started smoking within a few minutes of installation. If *nothing* works on the panel but you have power to it, then it may be a bum part.
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I do have power on the orange wire at the harness that plugs into the ac module (connector C230).
I attempted to see if there was power at circuit 141 which I believe is the fuse box in the door jamb. I tried using my voltmeter on the connector for fuse 12 (ac fuse) but couldn’t really get a reading. I’m assuming it should be getting 12v’s with the key in the “ON” position. I did see the brown wire coming from the rear of the fuse block but couldn’t follow it.
I looked underneath the dash and found the ground for G200 and it looks fine. I can’t see any visible corrosion and it appeared very tight. The wires coming off of it were both black and I couldn’t trace them back very far as it was so tight under there. It may be beneficial to unbolt the fuse block and try to get a better look at the back of it
And yes the module is a brand new one. I initially resolved it back in March of this year and I assumed it was bad. Bought the new one and installed it and the ac worked fine. When it stopped working a few weeks ago I got a warrant replacement module as I assumed the new part may have been bad. Clearly it wasn’t the issue now and may have not been the issue in March either. I replaced the blower motor and resistor at the same time.
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