Hi guys

so 4x4 decided to stop working. I have checked the fuses both dash and under the hood (15A and 30A). I've followed the wiring and it seems ok but I have a couple of questions for the electrical wizards as electrics is definitely not my strong point.

The plug that attaches to the small cylinder (assuming motor) beside the transfer case, if I test that plug with the 4WD switch to 4HI or 4LO what reading should I expect?

If I test the motor, do I test ohms and look for no resistance or mega resitance if the motor is shot?

Someone in a post mentioned relays for the 4x4, are they under the hood in the same place as the 30A as I got a bit confused as to their location. When testing a relay like these whats the procedure.

I have no other DTC and the 4x4 lights test correct on start up. I have manual hubs as i disconnected and blocked off the vacuum system because when I got the truck the pipes were FUBAR

I know it could be the dash switch, GEM, relays etc but I figured if I checked the motor and wiring at that end I could work back to the stuff I know even less about

Thanks in advance

 

We need to know the year model of the truck you are driving to proceed with advice and schematics.

 

I always forget that but - sorry! 2001 7.3 L XLT

 

A DC motor always works the same way. Apply 12 volts to wire A and ground to wire B and the motor spins forward. Apply ground to wire A and 12 volts to wire B and the motor spins in reverse.

The first test is to put leads on the wire (pins in the connector) in a way that you can see the voltage from the driver's seat. It would not make sense to constantly run a motor when all it has to do is spin a short distance and stop - so the duration of the voltage will be short. Once the meter is set up, put it in and out of 4X4 LO and watch the voltage. Reverse the leads on the meter as necessary.

 

Ok, here you go from the 01 manual:

 

 

 

 

 

Nice job Mike!!!

 

Mike, that is epic!

I didn't understand some but I do know I may now have been looking at the wrong connector by the TC. The one I pulled was attached to a cylindrical item on the exhaust side of the TC and has 2 connectors not the 6 shown. So I'll get under and have another look

 

Study what I have posted, and you will soon have a good overall understanding of the system. You have to obtain that understanding to have a chance at troubleshooting it.

 

If you can pull a DTC, I can post the troubleshooting procedures for that DTC.

 

I pull DTC's with a HYPERPAC and I don't know if it can pull stuff from the GEM but I have no DTC's at this point.

Would anyone know which box holds the relays? I have two boxes inboard of the main fuse box under the hood. Book says 40&41 but they seem identical to 38&39 which are related to towing and yay there's no numbers on them .

They could do with a contact clean so I'll start with that, proceed to check voltage at the two pin connection on what I'm assuming is the power supply to the TC motor to engage 4x4.

If understand correct the 6 pin plug is more sensors and logic control??

 

You are correct. That plug is a form of "communication bus" to the GEM. It shows the GEM what condition the Transfer Case is currently in.