Rear A/C Control

[Csides]

2005 Suburban 2500 8.1L. The rear A/C blower has stopped, no matter if I try to control it with the front console controls or the second row controls. I have checked the blower with independent 12v and it works. The wiring to the resistor has 12+volts and good ground. The resistor was replaced. The 30 amp fuse and the 10 amp ign 3 fuse are good. The purple wire that is for regulating voltage depending on fan speed and which routes to the resistor shows .1-.2 volts in the rear of the vehicle. Apparently this purple wire does not route to the second row controls, or at least I could not locate it.

I think I need to check continuity on this thin purple wire but I do not know where it comes from. I looked under the drive dash at the black control box but did not see a purple wire there. Obviously I do not have a wiring diagram. I suppose it connects to a different color wire somewhere in the harness?

Can anyone tell me the routing of this purple wire? Thank in advance for any help.

 

[Doubeleive]

2005 Suburban 2500 8.1L. The rear A/C blower has stopped, no matter if I try to control it with the front console controls or the second row controls. I have checked the blower with independent 12v and it works. The wiring to the resistor has 12+volts and good ground. The resistor was replaced. The 30 amp fuse and the 10 amp ign 3 fuse are good. The purple wire that is for regulating voltage depending on fan speed and which routes to the resistor shows .1-.2 volts in the rear of the vehicle. Apparently this purple wire does not route to the second row controls, or at least I could not locate it.

I think I need to check continuity on this thin purple wire but I do not know where it comes from. I looked under the drive dash at the black control box but did not see a purple wire there. Obviously I do not have a wiring diagram. I suppose it connects to a different color wire somewhere in the harness?

Can anyone tell me the routing of this purple wire? Thank in advance for any help.

If, everything else checks out then the culprit is usually the rear control module.

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[pronstar]

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[TJ Baker]

2005 Suburban 2500 8.1L. The rear A/C blower has stopped, no matter if I try to control it with the front console controls or the second row controls. I have checked the blower with independent 12v and it works. The wiring to the resistor has 12+volts and good ground. The resistor was replaced. The 30 amp fuse and the 10 amp ign 3 fuse are good. The purple wire that is for regulating voltage depending on fan speed and which routes to the resistor shows .1-.2 volts in the rear of the vehicle. Apparently this purple wire does not route to the second row controls, or at least I could not locate it.

I think I need to check continuity on this thin purple wire but I do not know where it comes from. I looked under the drive dash at the black control box but did not see a purple wire there. Obviously I do not have a wiring diagram. I suppose it connects to a different color wire somewhere in the harness?

Can anyone tell me the routing of this purple wire? Thank in advance for any help.

In other GM vehicle that I have the purple wire is the speed control signal from the HVAC module or the auxillary HVAC control module depending on which blower being addressed. The module provides a PWM GROUND signal, not a positive voltage.

 

[TJ Baker]

See diagram(s) 5 or 7 . Circuit #374.

Electrical Diagrams — 2005 Chevrolet Suburban 3/4 Ton 2WD V8-8.1L VIN G Service Manual | Operation CHARM

Detailed repair manual for the 2005 Chevrolet Suburban 3/4 Ton 2WD V8-8.1L VIN G.

charm.li

 

[Csides]

Thank you for your suggestions and links. Turns out this purple wire came out of a black box I think is called the rear auxiliary control module. The feed INTO this module from the front of the vehicle was dead. After several hours of testing, searching, drinking, many frustrating entanglements of my multi-tester probe wires and several temporarily lost tools (girlfriend claims is due to the the drinking, but I am not certain), and what feels like half of my interior disassembled, I traced this to an orange 12v wire in a 22-pin connector that is tucked away behind a kick panel to the left of the parking brake. The pins for this orange wire were burnt. See pic. Somehow this orange wire provides power to the rear auxiliary control module, but apparently is only done so through witchcraft because last night there did not seem to be a logical connection between this wire and the control module. Anyway, that problem is fixed. This evening I will attempt reassembly of the interior and finding the location of those tools. Thanks again for your comments and suggestions.

 

[TJ Baker]

Thank you for your suggestions and links. Turns out this purple wire came out of a black box I think is called the rear auxiliary control module. The feed INTO this module from the front of the vehicle was dead. After several hours of testing, searching, drinking, many frustrating entanglements of my multi-tester probe wires and several temporarily lost tools (girlfriend claims is due to the the drinking, but I am not certain), and what feels like half of my interior disassembled, I traced this to an orange 12v wire in a 22-pin connector that is tucked away behind a kick panel to the left of the parking brake. The pins for this orange wire were burnt. See pic. Somehow this orange wire provides power to the rear auxiliary control module, but apparently is only done so through witchcraft because last night there did not seem to be a logical connection between this wire and the control module. Anyway, that problem is fixed. This evening I will attempt reassembly of the interior and finding the location of those tools. Thanks again for your comments and suggestions.

I'll refer you back to the link I posted earlier, schematic #5 specifically. Over at the far right is circuit #1740. I'm fairly certain the 22 pin connector you found the issue in is C206 and the terminal is A6. That supplies 12 volt power to the auxiliary blower speed control and the rear blower itself. Due to the degradation of the terminals in C206, A6 you were able to see 12 volts at the controller but it would have failed a load test if you had tried to light up say a headlamp bulb or similar. This is why load testing is important instead of just reading for voltage with a test meter.

Connector C206 can be seen here in the link below as item 6 in the first listing.

C206 — 2005 Chevrolet Suburban 3/4 Ton 4WD V8-8.1L VIN G Service Manual | Operation CHARM

Detailed repair manual for the 2005 Chevrolet Suburban 3/4 Ton 4WD V8-8.1L VIN G.

charm.li

 

[Csides]

Thanks for the additional info and for yesterday's link. I tried to open the link yesterday but my work computer has firewall protections that prevented it from opening.

 

[TJ Baker]

Thanks for the additional info and for yesterday's link. I tried to open the link yesterday but my work computer has firewall protections that prevented it from opening.

It may be just as well, you got it traced out anyway.

Those online manuals that were linked are really useful but can be a bear to find what you need, unless you have spent some time learning where the stuff is located in the manual.

 

[Doubeleive]

Thank you for your suggestions and links. Turns out this purple wire came out of a black box I think is called the rear auxiliary control module. The feed INTO this module from the front of the vehicle was dead. After several hours of testing, searching, drinking, many frustrating entanglements of my multi-tester probe wires and several temporarily lost tools (girlfriend claims is due to the the drinking, but I am not certain), and what feels like half of my interior disassembled, I traced this to an orange 12v wire in a 22-pin connector that is tucked away behind a kick panel to the left of the parking brake. The pins for this orange wire were burnt. See pic. Somehow this orange wire provides power to the rear auxiliary control module, but apparently is only done so through witchcraft because last night there did not seem to be a logical connection between this wire and the control module. Anyway, that problem is fixed. This evening I will attempt reassembly of the interior and finding the location of those tools. Thanks again for your comments and suggestions.

welcome to the club been there done that lol, nice find on the burnt wire