Need Help 4x4 not working. 2007.5 Yukon SLT No service 4x4 light.

[Spoon Nthu]

I have replaced the switch, and I have replaced the front axle actuator. But neither of those have fixed it. I'm suspecting it was neither of those from the get go but wanted to check and make sure anyway I can always return those items anyway but I wanted to know what you guys think it could be. I'm suspecting the transfer case control module because with the switch it all the lights light up when first turning on the ignition, then when trying to change the position selector to another gear like auto or 4 hi the lights don't change it stays in 2hi. Any ideas????

 

[LordWayback]

sometimes the wires going from the front axle actuator go bad especially at the connector if you have a test light I believe you can check for 12v at the connector when it’s switched to 4wd and if you don’t get a glow either bad connector/wiring or 4wd fuse it’s also possible that you got a bad actuator even though it’s new

 

[Spoon Nthu]

sometimes the wires going from the front axle actuator go bad especially at the connector if you have a test light I believe you can check for 12v at the connector when it’s switched to 4wd and if you don’t get a glow either bad connector/wiring or 4wd fuse it’s also possible that you got a bad actuator even though it’s new

The fuse is good and there is no power at the connector when switching. But the switch doesnt try and change to 4wd if that makes sense. Like the lights don’t change or anything

 

[Fless]

Unless you like working in the dark, get a good bi-directional scanner on it that will work with the modules. Looking at live data and being able to command these modules to do things is the most efficient way to diagnose the cause.

 

[LordWayback]

The fuse is good and there is no power at the connector when switching. But the switch doesnt try and change to 4wd if that makes sense. Like the lights don’t change or anything

it is very possible that the switch is bad I can’t remember how to check with a multimeter if the switch is good because the 4wd should atleast blink whether it’s faulty or shifting into 4 wheel if you can confirm the switch is good and you can’t force it with a scan tool you can send 12v from one side to the other side of the wiring with a short finder harbor freight has one for $15 it basically provides power on one side and you use the other piece along the wire on the part you suspect a issue and eventually it signals a short where a wire repair is needed if you didn’t already fix it or the scan tool method didn’t work

 

[Spoon Nthu]

it is very possible that the switch is bad I can’t remember how to check with a multimeter if the switch is good because the 4wd should atleast blink whether it’s faulty or shifting into 4 wheel if you can confirm the switch is good and you can’t force it with a scan tool you can send 12v from one side to the other side of the wiring with a short finder harbor freight has one for $15 it basically provides power on one side and you use the other piece along the wire on the part you suspect a issue and eventually it signals a short where a wire repair is needed if you didn’t already fix it or the scan tool method didn’t work

I couldn’t force it with a scan tool. I tried bought a real nice one. I might try that short finder next

 

[Spoon Nthu]

Unless you like working in the dark, get a good bi-directional scanner on it that will work with the modules. Looking at live data and being able to command these modules to do things is the most efficient way to diagnose the cause.

I bought a scanner with bi directional control and it won’t force it into 4x4. Unless I’m doing something wrong

 

[LordWayback]

I couldn’t force it with a scan tool. I tried bought a real nice one. I might try that short finder next

if it won’t force it short of human error it may be wiring or the electrical shifter at the transfer case

 

[LordWayback]

I couldn’t force it with a scan tool. I tried bought a real nice one. I might try that short finder next

Depending on your exact year and model it may be a issue with this part they only ever occasionally go out but if you force it with a scan tool and it still won’t do it besides wiring this little motor that has to do with the transfer case may may be faulty

 

[LordWayback]

I couldn’t force it with a scan tool. I tried bought a real nice one. I might try that short finder next

If you would rather parts cannon this is a good video on that “motor”

 

[Fless]

If you would rather parts cannon this is a good video on that “motor”

Looks like he's working on the next gen SUV, so it's not the same.

 

[LordWayback]

Looks like he's working on the next gen SUV, so it's not the same.

they have a similar part that functions the same just installs differently this is their part if they were to parts cannon one on

 

[Spoon Nthu]

Depending on your exact year and model it may be a issue with this part they only ever occasionally go out but if you force it with a scan tool and it still won’t do it besides wiring this little motor that has to do with the transfer case may may be faulty
View attachment 429802I kept thinking it’s this guy or the transfer case control module. I’ll look into how to test this guy with a meter,or power probe. So I don’t have to parts cannon it.

 

[Fless]

A good bi-directional scan tool will show what's commanded vs. what is actual.

 

[LordWayback]

I think you can power probe a specific pin with it grounded and it’ll turn one way or the other like a blend door actuator however the scan tool is much easier as you can pull the motor off and command it to turn if it turns correctly while dismounted then it’s a transfer case issue

 

[LordWayback]

I don’t know if your model will work with the 2008 manual as you have a 2007.5 but most of the electricals 4wd wise should be the same pdf dump of a 2008 GM electrical book