2003 Envoy 4WD, 111K miles. Sometimes 4WD works fine. Sometimes, the A4WD light will blink for a few seconds and then light the "Service 4WD" light. Similar when switching to 4HI. I took it to a reputable shop in PHX. They found 19 codes in the TCCM. They cleared the codes and checked out wiring (based on TSB's they found online). They re-flashed the TCCM. Worked fine for a day or two and now its back to the intermittent "service 4WD". I don't think its the front axle disconnect or Transfer case actuator because I can hear them both when its working. Any suggestions would be appreciated.
4WD intermittent
- Thread starter e019404
- Start date
Has the transfer case fluid been changed religiously every 50k miles?
Can you remove the front axle actuator and test it a few times in midair?
Same with the encoder motor.
I'd highly suspect high friction in the encoder motor or the shaft it rotates in the transfer case.
The shop had a Tech II tool?
Can you remove the front axle actuator and test it a few times in midair?
Same with the encoder motor.
I'd highly suspect high friction in the encoder motor or the shaft it rotates in the transfer case.
The shop had a Tech II tool?
Voymom
Member
- Feb 3, 2012
- 2,523
I had this issue last winter, granted I had all normal engage and disengage sounds, but my light on 4WD wouldn't come on, nor did the 4WD kick in. We found after some investigation, that some how a wire had wiggled loose, once the wire was tightened up by my husband we had no more issues. Just a thought.
Transfer case fluid changed at 78K miles (110K currently). So its still within the 50K but due soon.
Prior to going up on ramps I switched from 2HI to A4WD. I hear a click up front but not the whine sound that you hear when the front actuator is engaging. A4WD blinks for several secs and then I get Service 4WD light. Drove it up on ramps. Same thing, click, no whine, blinking lights then service 4WD. Removed front actuator from spline disconnect to "try it in midair" as you suggest. Same results, click, no whine, blink, service 4wd light. I start the vehicle, back it down off the ramps, engine is running, I put it in neutral and now it works fine. The A4WD light blinked for a few secs but then I hear the whine and it successfully goes into A4WD. Then it successfully went into 4HI. Very confusing. Not sure what to try next. Thanks for the help and advice.
Prior to going up on ramps I switched from 2HI to A4WD. I hear a click up front but not the whine sound that you hear when the front actuator is engaging. A4WD blinks for several secs and then I get Service 4WD light. Drove it up on ramps. Same thing, click, no whine, blinking lights then service 4WD. Removed front actuator from spline disconnect to "try it in midair" as you suggest. Same results, click, no whine, blink, service 4wd light. I start the vehicle, back it down off the ramps, engine is running, I put it in neutral and now it works fine. The A4WD light blinked for a few secs but then I hear the whine and it successfully goes into A4WD. Then it successfully went into 4HI. Very confusing. Not sure what to try next. Thanks for the help and advice.
bravad'oh
Member
- Sep 15, 2012
- 44
Intermittent problems are the worst to diagnose. Grounds are a common spot of trouble and may be what Voymom's problem was. I don't know where the actuator ground is exactly but if you follow along the wiring harness you should see a wire some where that comes out and is bolted to the frame of the truck. Ubolt it and clean it up and the spot it bolts to. Also check the connector at the actuator for corrosion. The Roadie posted an awesome decsription and repair that you should look at. I don't know how to link it but if you search: ( Repairing Front Axle Actuator, and theory of operation ) you should find it.
bravad'oh
Member
- Sep 15, 2012
- 44
I had a look at the wiring diagram and it looks to me there are alot of other things that share the same ground as the actuator, over on the left side of the engine. You would notice if all of that stuff wasn't working. In addition to the plug at the actuator, there is a connector by the transfer case you should check as well.
Voymom
Member
- Feb 3, 2012
- 2,523
bravad'oh;95670 said:
What I do know, is that my husband was doing some electrical work near the 4x4 electrical components the morning before we had our issue, basically every time we drove it wiggled the wire connection loose and all we needed to do was tighten it.
:wootwoot:I removed the front axle actuator. Disassembled it to look for obvious damage and cleaned the internal electrical contact surfaces. Cleaned and checked the front axle actuator connector and checked for loose wires. Reassembled and reinstalled actuator. Click, no actuation and service 4wd light (same as before) with the actuator in "mid air" and installed into the spline disconnect housing.
Took it for a short drive and then it seemed to work normally. I can hear the normal engagement sounds and no service 4wd light. I still don't think its fixed for good. I have a new actuator on order.
Took it for a short drive and then it seemed to work normally. I can hear the normal engagement sounds and no service 4wd light. I still don't think its fixed for good. I have a new actuator on order.