4wd System Operation & Help Thread

Check it for power at connector PD Pin 6 (Green/White), if nothing there then go to PB Pin 8 (Green/White or Blue/White).

 

Shouldn't matter, on a properly functioning system you should be able to go straight from 2H to 4L and back with no issues.

 

Went to unplug my neutral safety switch and now the car won’t start, very difficult to unplug. I’m thinking it was corroded on the inside and not pushing all the way down. Going to replace this

 

Yea it's in a crappy spot and even more crappy to remove because it tends to corrode tight to the shaft.

 

Hmmm i thought you couldnt go from 2h to 4lo, that you had to be in 4high before shift to 4lo
Now ill have to try

 

It tends to be easier to get into 4L from 4H because that part is already in gear but if everything lines up it will go right from 2H to 4L no problem.

 

I just backprobed my ecu and when cold, it checked out, pretty well. Then went for a drive and tested again and values changed. 4wd in 4hi, which should be 0v is 12v, DL1 which should be 12v is 0v, DL2 should be 0v is 12v, and ADD should be 0v is also 12v. When cold it did struggle to shift into 4 for a bit, and values changed, but once it shifted they became correct. My question now is, where does this lead me? Where should I begin to look next? Thanks in advance!

 

It sounds like either the Transfer Case Actuator is failing when it gets hot or one of the motor wire (TM1 or TM2) is going open circuit when it gets hot.
If you have backprobes you can backprobe TM1 (Pin 2 Green) and TM2 (Pin 1 Blue) at the Transfer Case Actuator connector, put a test light across them, and see if the light lights while you have someone operate the 4wd.

 

Just ordered a test light, I’ll try that next weekend. I’m assuming I backprobe 1 and 2 and run the test light across both pins? Or do I individually backprobe and test the pins?

 

backprobe each to ground.

 

They should be 12 as well, correct?

 

depends on where the motor is, check the first post in thread with the spreadsheet

 

I'd put it across them first, if it lights and the actuator doesn't move you know your wiring is good and the actuator is bad.
If it doesn't light then do the same check on TM1 (F13 Pin 2 (Green)) and TM2 (F13 Pin 1 (Blue))at the 4wd ECU

 

I quickly backprobed both pins while having someone flip the switch. Pin 1 I saw 0.9 and pin 2 hit 12v for a second. I’ll double check everything when I get the test light in and go from there

 

wow there is a wealth of knowledgable techs and do it yourselfers. Need help also...
Background on my truck i bought it used 3 years ago never really engaged perfectly but always eventually engaged until last offroad trip. then it wouldnt go back to 2wd. Had no light to go into 4 hi and would sometimes engage in 4 lo only. now it wont go to anything. I suspected the switch and one of the tabs is broke not making contact< but im not sure if I caused it or not. Here are the readings before i removed the 4x4 select switch

 

here are my results

 

ADD being at 0v but DL1 & DL2 being correct suggests the ADD is staying locked in for some reason or there's a problem with the ADD switch or circuit.

Did you check if the front axle is indeed locked in?

 

I could spin the front drive shaft freely by hand. I never had the ADD apart. So far I ordered a new selector switch due to the cracked housing. Had the t-case actuator out, cleaned and lube and bench test motor.

Last night while applying pressure to switch and engage everything worked. 4-hi, 4,lo and back. Once the switch gets here later this week, I’ll retest everything again to see if something wrong with ADD.

 

Before all this I could not always get the 4x4 Hi light to come on.