SERVICE 4WD message

[Pepper]

2005 Tahoe with “4WD SERVICE “ message just came on after replacing the fuel line from pump to steel line that goes to injectors. Had to drive into my car ramps in garage to get better clearance.The only thing I did to the power train was unbolted the driveshaft and swung it over so I could get my head above the tank (loosened both tank straps) to unhook the fuel line and replace with new line .Now I will say that when I took U-bolts out at yolk I had to use a plybar to separate the universal joint.Wasn’t much pressure but once it was out of yolk the shaft moved easily in and out of housing but I never removed it from its splines. After finishing up my fuel line replacement I set the U-joint back in place,just like it came out.Had to tap the joint just a little to go back in the yolk but nothing that hard.Just a tap here and there and finished getting the U joint seated by tightening the 4 bolts to draw it into place.Could I have accidentally cause something to make that MESSAGE appear on my dash.Is there any wires I could have pulled?
I wasn’t even around the transfer case.Any ideas would be much appreciated. Thx

 

[strutaeng]

Could be simple coincidence. The transfer case doesn't switch at all?

Have you checked the fuses and the grounds?

 

[Pepper]

it does transfer,and no I’ve not checked the fuses.According to owners manual it says when u get this display take it to your local dealer. Not happening.

 

[George B]

Check the plug on the transfer case shift motor. You were working near there and may have disturbed it.

It’s hard to diagnose this without a scan tool to read the code that is causing the service message.

 

[Fless]

The encoder motor has a short pigtail with the connector that mates with the body harness. When they're mated they should be clipped above the driveshaft on a bracket.

Like @George B noted, you can inspect that connector for pin fitment and making a solid connection. Also find a scan tool that will read the 4wd codes and you'll be much closer to a solution. Attempting to diagnose without that info is doing it blind.

 

[Pepper]

I’ll do guys,thx

 

[Pepper]

now the traction control light came on and g to here’s no lights j ok n the switch on the console switch

 

[Pepper]

it’s like it does it sporadic.Yesterday driving it it in the rain stabilized disengaged message with the TC light on.
Going to pull into garage and look at the pin fitment as mentioned

 

[Pepper]

just noticed when I bolted my shaft back my marks are 1/2 rotation off.My marks are still there and it’s 180 degrees off.
Hopefully that will fix it.

 

[Fless]

If you're talking about the front propshaft u-joint it won't make a difference to the electronics.

 

[Pepper]

it’s the rear.There’s a small bracket between the cups on the u -joint,it’s like a small 1/4” wide bar that each end slides into the joint.Well when I was using my pry bar to separate the universal joint ii broke just one end of the part( not sure what u call it,but the parts store sells them)so I used a flat screw driver and sorta put it back in place.Whle I was under there I unhooked the decoder and plugged back,and there are 2 ground wire on the drivers side on the frame that were rusted.So I cleaned them and drove it last night with messages and NO TC light came on. Will keep updated.

 

[blackbeard_lives]

ive got the service 4wd light on my new to me 02 gmc 1500HD, gotta rebuild the 4l80e first, no reverse and fixing the servo pin didn't fix it must be a bad reverse band, was gonna look into the 4wd light after i get the trans working again but noticed this post and am glad to see one fix found, will try to find my fix another day.

 

[Fless]

ive got the service 4wd light on my new to me 02 gmc 1500HD, gotta rebuild the 4l80e first, no reverse and fixing the servo pin didn't fix it must be a bad reverse band, was gonna look into the 4wd light after i get the trans working again but noticed this post and am glad to see one fix found, will try to find my fix another day.

It will help your diagnosis to get the 4wd code(s) that triggered the service light.