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goodwrench9124, ASE Certified Technician
Category: GM
Satisfied Customers: 3432
Experience:  37 years of dealership exp. Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer
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99 GMC Suburban: 4WD...I need a wiring diagram for the transaxle

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I have a 99 GMC Suburban 1500 4WD. I need a wiring diagram for the transaxle. I have a hanging plug with 6 wires on it. I do not see where it goes but there are 3 bare wires coming directly out of the transaxle. The SERVICE 4WD light is on the dash.
Hello and welcome, are you referring to the transfer case connector?
Customer: replied 7 years ago.

Yes, sorry I'm not a mechanic. You're right it's the transfer case. The part the acutates the 4WD.



Ok, here is a picture of the connector location. also included what the wire colors are. if there is more info you need, please let me know.





(1)Vehicle Speed Sensor (VSS) Connector
(1)Vehicle Speed Sensor (VSS) Connector
(2)Harness Bracket
(2)Harness Bracket
(3)VSS Connector
(4)Rear Propshaft Speed Sensor Connector
(5)Rear Propshaft Speed Sensor
(6)Automatic Transfer Case
(8)Front Propshaft Speed Sensor
(9)Front Propshaft Speed Connector
(10)Left Frame Rail
(11)Encoder Motor Connector
(12)VSS Harness
(13)VSS Adapter Harness Connector







Wire Color

Circuit No.





Transfer Case Encoder Signal Return




Transfer Case Postion Switch Encoder Signal - Channel A




Transfer Case Postion Switch Encoder Signal - Channel C




Transfer Case Postion Switch Encoder Signal - Channel B




Reference Voltage Feed - 8 Volt




Transfer Case Postion Switch Encoder Signal - Channel P

Customer: replied 7 years ago.

That looks good. Do you also have a picture of the male end of the plug shown with the color of the wires. There is only 3 wires hanging down. The plug is the one shown.




even GMs books are not showing the male end, but the color of the wire location should be the same as the picture i posted earlier.



goodwrench9124 and 3 other GM Specialists are ready to help you
Customer: replied 7 years ago.

OK,, I think I almost got it figured out but I am missing something. Basically, I need to know how the 6 pin connector connects to the three wires. Am I missing 3 additional wires or do the 4 encoder signals go through one wire? That's the only way I can make sense of it.

Will the manufacturer have the male end with a schematic?



P.S. when I'm done with this, I have a few other problems I need to iron out on this vehicle. Do you do AC work too?

sorry, I wasn't thinking straight. the 6 way connector plugs into the encoder motor. all 6 wires should be in the connector. are you saying there is three wires missing from the connector?



Customer: replied 7 years ago.
The female end has all 6 wires going into it. The male end is missing and there are three wires hanging out of the transfer case not connected to anything.
in the picture I first posted, can you post me the number of the connector where you see these three wires that are not connected to anything?
Customer: replied 7 years ago.

Looks like might be around #9. hard to tell with that pic. There are other wires coming out of the same area but they are properly connected to a plug


number 9 is a prop speed sensor connector, what are the color of the wires?
Customer: replied 7 years ago.

I got Black with a white stripe

Brown with a white stripe

Green with a black stripe

ok, these are wires for the transfer case encoder motor. do you happen to have a digital camera to take a picture then upload to me? if not, do you see where the the 6 way connector plugs into the transfer case?
Customer: replied 7 years ago.

I will try...


Ok, if not. we will try a different approach. is this something than can wait until tomorrow? I will be logging off, but I can let another expert help?
Customer: replied 7 years ago.
Here comes the pics..............graphicgraphicgraphicgraphicgraphic
Customer: replied 7 years ago.

Yeah, it can problem. I think I am far from getting this fix at this point.




Customer: replied 7 years ago.
Relist: Good info but the Tech is not online at the moment.
Good info but the Tech is not online at the moment