4wd help
Lead Driver
Joined: Apr 2011
Posts: 8,259
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From: Northern California
Do this,
With the vehicle in park and in 2 wheel drive crawl under the front and turn the inner axle shaft at the ujoint, it should be stiff but with some force will rotate. This confirms the transfer case is in 2wd and the hub are unlocked.
Now drive at 10mph and switch to 4x4 high, if the dash 4x4 light comes on pull over in a short distance ( don’t want to drive in 4x4 on drive pavement ) somewhere that you can crawl under the front.
grab the inner axle again and try to turn it while a helper watches the opposite side.
if it turns the transfer case is in 2wd
if it doesn’t turn then the transfer case is in 4wd but 1 of your hubs is not engaging
have your helper watch the opposite side inner axle to see if it turns,
if it does your hub is not locking.
the vacuum hub system either had a vacuum leak or the hubs are stuck and needs servicing or replacement
that your center caps off and try to manually lock the hubs,
With the vehicle in park and in 2 wheel drive crawl under the front and turn the inner axle shaft at the ujoint, it should be stiff but with some force will rotate. This confirms the transfer case is in 2wd and the hub are unlocked.
Now drive at 10mph and switch to 4x4 high, if the dash 4x4 light comes on pull over in a short distance ( don’t want to drive in 4x4 on drive pavement ) somewhere that you can crawl under the front.
grab the inner axle again and try to turn it while a helper watches the opposite side.
if it turns the transfer case is in 2wd
if it doesn’t turn then the transfer case is in 4wd but 1 of your hubs is not engaging
have your helper watch the opposite side inner axle to see if it turns,
if it does your hub is not locking.
the vacuum hub system either had a vacuum leak or the hubs are stuck and needs servicing or replacement
that your center caps off and try to manually lock the hubs,
New User
Joined: Apr 2019
Posts: 4
Likes: 0
That's some good simple tests. Thanks Pirate 4x4. Sounds like me and you Csmith are in a little different boat. If your light is coming on then your transfer case is probably engaging. I would guess a vacuum problem, solenoid, or hub problem now. I was asking about a scan too because you can see if the Gem is seeing correct switch input. Sounds like you found the switch to be bad and replaced it.
For me I'm not getting any indicators in the dash other then proving out. Correct me if I'm wrong but I don't think the Gem is sending signal to my low to high and high to low relays. My switch is giving correct signals btw. I used a test light, hooked it up to power, and set it in the circuit coming from Gem to relay to test if the Gem is grounding the relay. Vehicle KOEO and KOER neutral brake on and no light of the test light.
I saw a lot of people have problems with water corroding the fuse box and Gem module. Thinking about tearing it apart and rebuilding the fuse box. Saw a great write up on here about it.
Any thoughts would be much appreciated!
For me I'm not getting any indicators in the dash other then proving out. Correct me if I'm wrong but I don't think the Gem is sending signal to my low to high and high to low relays. My switch is giving correct signals btw. I used a test light, hooked it up to power, and set it in the circuit coming from Gem to relay to test if the Gem is grounding the relay. Vehicle KOEO and KOER neutral brake on and no light of the test light.
I saw a lot of people have problems with water corroding the fuse box and Gem module. Thinking about tearing it apart and rebuilding the fuse box. Saw a great write up on here about it.
Any thoughts would be much appreciated!
New User
Joined: Apr 2019
Posts: 4
Likes: 0
Well I thought I would update you all with what I found. Finally figured it out. I found the upper connector on the transfer case was unplugged. Embarrassing a little. The connector was on and looked plugged in but wasn't clicked all the way on. Cleaned it out, plugged it in and tested and now truck shifts into 4wd. Still need to fix the vacuum system but that's easy. $wd works with the hubs locks. I guess with that open circuit causing codes in the Gem it stops sending signal to the relays. Pretty sure that's why I wasn't seeing signal from Gem to energize the relays.
Csmith you ever figure out your truck?
Csmith you ever figure out your truck?
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New User
Joined: Apr 2019
Posts: 7
Likes: 0
Just got back into town and am gonna try and get some readouts tomorrow after work and go from there. Sorry I wasn’t clear on light working, my dash indicator 4x4 light has not and still does not work. I was stating light on the 4x4 switch was illuminated (old fart mechanic years ago said if it lights up its hot all you gotta do is hit lights and if you don’t have a meter) I’ve since realized there is a multitude of variation from his original theory. Bottom line I am live at actuator, live at plug for T/C but I need to see how much power it’s getting I guess!
New User
Joined: Apr 2019
Posts: 4
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Well that sounds a lot more like the situation I had now that you say it wont engage. If you get a scan tool first pull codes but next it would be good to watch pids and check to see that the Gem is getting correct switch input and command the instrument cluster indicator lights on with the scan tool.
You said the lights are proving out when you start the truck or not?
And you said you replaced all the relays but what about the two by themselves in a taped relay box right next to the fuse box under the hood?
If its easier you can Pm me and we can trade contact info. Sometimes phone is easier. I can get wiring diagrams or anything like that you need.
You said the lights are proving out when you start the truck or not?
And you said you replaced all the relays but what about the two by themselves in a taped relay box right next to the fuse box under the hood?
If its easier you can Pm me and we can trade contact info. Sometimes phone is easier. I can get wiring diagrams or anything like that you need.
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