Fuse Box Question

[miller87]

Hello. Just bought my 1998 Tahoe yesterday and the power locks do not work (which means I cannot even open the back doors). I assumed it was just a fuse as the seller played dumb and also mentioned the fuse. Anyways, I opened the fuse box on the side of the dash and see that there are 24 fuses. According to the diagram, the Power Accessory (which I would assume is the locks) is listed without a number, instead it has the letter, "A" next to it. I see no place for the power accessories anywhere in this fuse box. I noticed there are two of the larger, metal relays on the left hand side - Could that be it? The diagram says it's a 20 and 30 amp. There is PWR ACCY (P/U) and PWR ACY (UTIL).

Power Windows work just fine, and are listed just below the pwr accy's on the diagram with the letter, "B".

Very confused. Any help would be greatly appreciated.

 

[lesterl]

2 Door:
Schematic for my 1995 tahoe shows a 20A circuit breaker labeled "PWR ACC" There should be 12vdc on either side of this breaker all the time the battery is hooked up. There appears to be no fuse for this circuit. If you have 12vdc present on either side continue on.

Pull the door switch from the drivers door, check orange wire to ground should have 12vdc. Black wires to Orange should show 12vdc. If that is good, measure across the Lt Blue and White wire and press the lock or unlock, one way will show 12vdc, other way will show -12vdc, no button pressed will show 0vdc.

If all this shows good then you need to go to the passenger door and check the Lt Blue and White wires again. If those wires at passenger switch (pressing the drivers switches) test good then check across the grey and tan wires from the passenger switch, this is the feed to the motors, should see the 12/-12/0vdc like the other 2 pairs checked.

4 Door:
30A Circuit Breaker A supplies power to orange wire at the relay bank (Right Side of Brake Pedal Bracket, probably could feel it click when button pressed), 20A CIG LTR Fuse 13 supplies 20A to Orange wire at lock switches.

At Passenger or Drivers Switch Orange wire 12v to ground, when a switch is pressed Lock will put 12v on LtBlue wire, Unlock will put 12v on White wire. The Relay bank White wire is Unlock and Lt Blue is Lock, either should go high when the corresponding button is pressed either drivers or passenger side.

At Relay Tan and Grey wire will have 0v, pressing a button should put 12v on either White wire or Lt Blue wire and cause either a 12v or -12v output to the lock motors. Orange wire has 12v all the time, Black wire should be ground, 12vdc between orange and balck.

Clear as Mud?

If at any point something doesnt read right, start troubleshooting from there..... otherwise post back and let us know what it was.

 

[miller87]

I'll be trying it out tomorrow. Thanks very much for the reply.