“Service 4WD” message

[Fless]

Switch measurement procedure here, starting at about 2:10 into it.

Auto4WD = 61.7-68.1 ohms
4HI = 656-760 ohms
2HI = 1.50-1.53 K ohms
4LO = 2.32-2.37 K ohms
Neutral = 1.015-1.035 K ohms

Pics of switch internals. On the last pic, reflow the solder on the pins in the rectangles, and clean the switch pads (circled) with isopropyl alcohol, eraser, etc. Also clean the contact points in the black rubber strip with alcohol.

 

[George B]

Switch measurement procedure here, starting at about 2:10 into it.

Auto4WD = 61.7-68.1 ohms
4HI = 656-760 ohms
2HI = 1.50-1.53 K ohms
4LO = 2.32-2.37 K ohms
Neutral = 1.015-1.035 K ohms

Pics of switch internals. On the last pic, reflow the solder on the pins in the rectangles, and clean the switch pads (circled) with isopropyl alcohol, eraser, etc. Also clean the contact points in the black rubber strip with alcohol.

View attachment 250671

View attachment 250672

View attachment 250673

Perfect! Thats the one I was looking for.

 

[Fless]

I found an OE switch at one of my local UPulls ($5), cleaned it up and replaced the backlighting, and checked the resistance. So now I have an OE spare.

I wish that would have been the problem with mine, but it was the encoder motor. From my research, only Dorman makes the encoder motors new but I think they have a lifetime warranty.

 

[LTG515]

Switch measurement procedure here, starting at about 2:10 into it.

Auto4WD = 61.7-68.1 ohms
4HI = 656-760 ohms
2HI = 1.50-1.53 K ohms
4LO = 2.32-2.37 K ohms
Neutral = 1.015-1.035 K ohms

Pics of switch internals. On the last pic, reflow the solder on the pins in the rectangles, and clean the switch pads (circled) with isopropyl alcohol, eraser, etc. Also clean the contact points in the black rubber strip with alcohol.

View attachment 250671

View attachment 250672

View attachment 250673

That video is a super nice explanation! And pretty comical too haha thanks for that, it was helpful. I’ll get my hands on a multimeter and have a go.


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[Fless]

That video is a super nice explanation! And pretty comical too haha thanks for that, it was helpful. I’ll get my hands on a multimeter and have a go.

If it fails the resistance test, disassemble, clean, and re-check it.

 

[George B]

If it fails the resistance test, disassemble, clean, and re-check it.

But flow the solder either way. It is an intermittent problem that could hide while your testing.

 

[TJ Baker]

There are 8 different code status' for your vehicle and you never know which code groups the scanner is requesting.

With your 2004 a $12 Chinese elm327 clone and the right smartphone app you can read those codes yourself. I use the Veepeak mini Bluetooth OBD Scanner as well as several others and the Car Gauge Pro Android app on my 2005 Yukon. The Car Gauge app is a little quirky but will read practically all your codes from all of your modules. It might save you a good deal of diagnostic time as well as not replacing parts that are working fine.

https://www.amazon.com/gp/product/B011NSX27A

 

[TJ Baker]

Also,,, often the motor and brake of the transfer case shift motor (encoder motor) works but the range position sensor is at fault. That part is available separately and is a good deal cheaper than replacing the whole encoder motor assy. The sensor is beneath the larger gear in this pic....

 

[Fless]

Next one of those encoder motors I see at the UPull will be mine -- haven't seen one yet -- and I'm going to dissect it. Possibly put a new range position sensor in it and give it a try. I know the wiper contacts get worn inside. Not that I need one right now....

 

[TJ Baker]

Next one of those encoder motors I see at the UPull will be mine -- haven't seen one yet -- and I'm going to dissect it. Possibly put a new range position sensor in it and give it a try. I know the wiper contacts get worn inside. Not that I need one right now....

Those wipers can get coated with crud as well as cut into the 'home' position of 2Hi on the resistive material they ride against..