MultiMode 4wd Issues - blowing 20A fuse

[KHoffRunner]

I finally had to the time to get under the truck and hopefully end the long saga of chasing 4wd issues, but now I'm blowing the 20 amp 4wd fuse in the cab fuse box.

Back story: A few months ago when trying to exercise my 4wd after the truck being in garage getting new rockers for a long time, and I got the flashing lights of doom. I believed it was my actuator - for a long time it would squeal when going into 4wd. It didn't squeal this time. One time about ten yrs ago my knee hit the button going 60 mph for several miles and ever since I felt like I was on borrowed time. I pulled the actuator and it failed a bench test, on further inspection the magnets in the motor cover had come unglued and the copper windings looked burned. I think the motor over heated and melted the epoxy.

I found a used actuator, which are very hard to find for a '00 multi mode, and it bench tested fine. While tracking down the actuator I pulled the front actuator to test the sensor. The blue vsv solenoid was also getting hot so I replaced both the brown and blue solenoids in the engine bay.

Today, I timed the actuator to 4wd, the shaft on the tcase all the way in, and the front actuator is in 4wd. Started the truck up and got no lights. I thought this was improvement, thinking maybe it needed a minute to recognize where everything is at. Well, it's popping the 20 amp fuse immediately.

This leads be to believe the pig tail on the front actuator has a short or the 4wd ecu has gone bad. I thought it was directly off the wiring harness, but I found that its a pigtail that connects under the oil cooler.

I feel like when the actuator failed it cause a chain reaction series: Actuator failed -> Blue VSV burned up (or the short in the pigtail could be causing this)

Has anyone had issues with their truck popping the 20A 4wd fuse? Honestly, I'm thinking about going to manual hubs, assuming I can with multimode?

I appreciate any help, this has been a long nightmare.

 

[2TH4IST]

Checking my 2000 wiring diagram book, that 20a fuse feeds the 4wd ecu and the rear diff lock ecu (if you have the rear e-locker). Power is distributed through the 4wd ecu to the 2-4 select motor and to the vsv valve 2wd, add (closest to the firewall).

So somewhere you have a dead short to ground. Either a component failed or a wire is shorted out.

When you were replacing the rockers, by any chance did you cut or nick any wiring?

 

[spartacus]

This diagram may help

 

[KHoffRunner]

Checking my 2000 wiring diagram book, that 20a fuse feeds the 4wd ecu and the rear diff lock ecu (if you have the rear e-locker). Power is distributed through the 4wd ecu to the 2-4 select motor and to the vsv valve 2wd, add (closest to the firewall).

So somewhere you have a dead short to ground. Either a component failed or a wire is shorted out.

When you were replacing the rockers, by any chance did you cut or nick any wiring?

I put in a new front ADD actuator today, a good switch, and was really hopefully my my issue was through there. I even grabbed another 4wd ecu. Unfortunately, it wasn't either of those.

I'm trying to isolate the issue. I put my old VSVs back on and it still. Off to get more fuses..... T/c actuator and is about all that's left to check.

I do have the console apart because I replaced the top 4wd position sensor, but I don't see anything grounding through there.

Next order is to isolate the

 

[KHoffRunner]

This diagram may help

Thank you. I have a replacement actuator that bench tested with confirmed good switches. I have everything timed for 4wd at the moment. Maybe I'll try timing it to 2wd, and see if it blows when trying to engage 4wd.