1999 gmc jimmy 4wd does not work. at start can hear several clicks then service 4wd light comes on.?

Question

Encoder? Module? cant seem to find problem, where do I look first. Can I get codes myself, what pin do I ground for codes?

To follow up, the car runs fine, not a starter solenoid problem. I pulled the trans fuse for several minutes (car off) and did the dance with the ignition switch 5 times. All the lights on the 4wd panel will light, then 4 hi and 4 low go out after several seconds. the rest stay lit, including the service 4wd light until the next time I start the car up. Then I get several clicks again, all the lights on the 4wd switch panel go out and the sevice light stays on.

Answer 1

i own a repair shop and there's a sensor on the 4 wheel drive unit that senses if it locks in or not,what its doing is locking in,and then coming out again this is caused b the actuator for the front differential unit,,once it kicks out it triggers the sensor that its not working you don't need a code reader for this one,,ask at any auto zone ,and they can scan it for free,and they can also get you a new actuator for it,,they run around 70 bucks for a new one,,this is a common cause for the Chevy's and GMC,s,i have a gm tech certification,so i have encountered this a few times,,good luck with it,i hope this help,s.

Answer 2

Unfortunatley you will have to get the code by using a scan tool. I am not sure if an aftermarket scan tool will read the ATC (automatic transfer case) module. here are a list of codes.
once you find the code email me and i will send you the wiring diagram and diagnosic flow chart for the code that is setting.

Anyone of these codes setting could create the problem your having.


Diagnostic Trouble Codes

DTC B2725 ATC Mode Switch Circuit Malfunction

DTC C0300 Rear Speed Sensor Malfunction

DTC C0305 Front Speed Sensor Malfunction

DTC C0308 Motor A/B Circuit Low

DTC C0309 Motor A/B Circuit High

DTC C0310 Motor A/B Circuit Open

DTC C0315 Motor Ground Circuit Open

DTC C0323 T-Case Lock Circuit Low

DTC C0324 T-Case Lock Circuit High

DTC C0327 Encoder Circuit Malfunction

DTC C0362 4LO Discrete Output Circuit High

DTC C0367 Front Axle Control Circuit High

DTC C0374 General System Malfunction

DTC C0376 Front/Rear Shaft Speed Mismatch

DTC C0387 Unable to Perform Shift

DTC C0550 ECU Malfunction

DTC C0611 VIN Information Error

Answer 3

This is not easy to diagnois. First thing you could try is to unplug the module for a while and then reconnect it I have seen these things go into logic lock-up and do what your describing.I think it is on passengers kick panel If this doesent work you will need to have a dealer tech ck it out.

Answer 4

First I would look for a solenoid (relay) between the battery and starter; you may be able to jump over it; use caution, it will spark and will be cranking the starter; next, get a Chilton's auto manual from the library - it will tell you exactly what to do, step by step