Hi, this is a great site and have enjoyed checking out everyone’s trucks over the past year. However, I am in need of some assistance, I have an 06 Screw 4x4, with 25,000 miles on it and the warranty expired last month. The local dealer I bought the truck from, wants $98.00 just to diagnose the problem.
I have the factory wiring diagram manual and have been troubleshooting the problem up to the point where I think it might be in the PCM, I started out by ohming out the switch on the dash and even replaced it with a new one, BTW, they both ohmed out the same.
I ohmed out the plug/harness at the PCM while switching to 4 hi, 4 lo and 2 hi and have the same readings, that tells me that harness from the PCM to the selector on the dash is good.
I ohmed out the harness between the PCM and the transfer case motor relays, it's Ok, I can put the dash switch into either 4 hi or 4 lo, and at the CW relay or CCW relay for the shift motor on the transfer case ground the relay coil (which the ground wire comes from the PCM) and it will switch the transfer case into the range selected, as soon as it shifts, I remove the ground, and does display the range selected on the dash. now here’s the kicker, after it is engaged into either 4 hi or 4 lo, I can select at the dash between the two ranges and it will shift the transfer case with no problems, but once I move the selector to the 2 hi position it won't allow me to go back into 4wd unless I temporarily ground out one of the relays. I have measured the voltage at the relays while shifting the selector on the dash between the ranges, the voltage is good at 12 vdc for the brief moment while the relays activate long enough to shift and engage the transfer case. It would at intermittent times switch from 2wd to 4wd during my testing but hasn't since. The fuses are good and the relays checked out. OK, ............ any Ideas? Thanks in advance for you input