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4wd Actuator

Let me rephrase that. I think the other half of that circuit gets energized with the 8V source when the 4LO switch is actuated, letting that 8V go through the closed switch and to the coil that energizes the relay and closes its contacts to provide a high amp flow 12V to the Actuator Motor to give you 4LO. At least that's what makes sense without diving into the manuals wiring diagrams, which I can't do since I'm currently at work to 10 tonight.
 
Big T said:
Well went out an did more tests and concluded I need a new tester as the pins are too short on what I’ve got. No success at the plug to the encoder motor.

Got under the truck in the front with help pushing buttons above and nothing happening at the actuator. Pull the actuator and it is stuck in the 4WD lock position. Did some tests at the plug with a test light and I’ve got power there using the ground in the plug. It’s not switching off to the other leads that move the actuator.
Click to expand...
Got the replacement actuator and confirmed it’s working when plugged into the harness. So much fun laying on cardboard and doing this in -9F temps. Old actuator packaged up for warranty return.

Temps supposed to be warming up after today.
 
Alright doing some detailed testing starting with Transfer Case Connector Switch C1:

1675623930804.png1675624090361.png

I believe this connector attaches to the switch buttons at the dash. The # of pins is an exact match and shape, but the color coding of the wires does not match. For example, the G (ground) pin has a Red wire, when it says Black above. The F pin has the black wire.

I tested with the plug off and the only combo I got voltage for was G to A at 8.0v. B, E, H got 0.1v; C, D, F got 0.0v.

I then performed tests 1 and 2 from the following:
1. Select 4WD low, test voltage backprobed at the transfer case motor drive circuits, C1 terminal A to terminal B. Should be battery voltage for as long as the 4WD Low indicator is flashing.

2. Test voltage backprobed at the motor brake control circuit C1 terminal D. Should be battery voltage until 4WD Low is selected, then voltage should be 0 or near zero while the 4WD Low indicator is flashing.

3. Scan the encoder switches status. Test voltage backprobed at the encoder switches circuits. Compare to the information in tech tips. Compare when selecting 2WD, 4WD High and 4WD Low.

4. Repeat tests at Transfer Case Shift Control Module connectors.

5. Inspect C131 and C132 connectors, terminals, wiring for damage, corrosion.

6. Test wiring from Transfer Case Shift Control Module to in-line connectors, to transfer case encoder motor.
Tech Tips:

1. A to B in 4 Lo got me voltage Fluctuating from 2V to 6+V when it should be full battery voltage.


2. Terminal plus Ground to under dash got 8.0v in 2 Hi when it should be battery voltage and 8.0v in 4 Lo when it should be 0 or near Zero. Obviously, this is problem.

3. Not sure where the encoder switches are? Is this the other plug on the dash switch/buttons?

Still need to do 4, 5, and 6.
 
The final tests on C1 were done in a snow flurry. We leave tomorrow. Hoping to negotiate working from home in MT between assignments, which would have me up Mid-March to Mid-April.

Husker 6.5 I really need that disk to access the manuals as I’ve only got part of the descriptions. Missing the part: if this then skip to there.

The one circuit with fluctuating voltage, not full battery voltage is the one obvious issue, but I don’t know what that means.

Until I get back up again, it’s 241-C transfer case rebuild in Fullerton after I cut up the fallen eucalyptus tree.
 
1. Select 4WD low, test voltage backprobed at the transfer case motor drive circuits, C1 terminal A to terminal B. Should be battery voltage for as long as the 4WD Low indicator is flashing.

A to B in 4 Lo got me voltage Fluctuating from 2V to 6+V when it should be full battery voltage.

I did this test several times with the same result. Any idea what could be causing the incorrect and fluctuating voltage here?
 
Big T said:
But A to G (ground) worked perfectly.

B is circuit 1693 which comes from the Transfer Case Control Module to the switch:

View attachment 79529
Click to expand...

Weather was not allowing me to properly test at the Transfer Case Control Module (TCCM) as it’s tucked up under the dash on the left side of the steering column. I will do some thorough testing when I get back up. Kinda pointing at the TCCM and it is a Dorman reman unit. I’ve seen good used ones on eBay for $42.
 
those electro-digical boxes can do some funky things as they age. my original PCM on my truck I found could not control the wastegate solenoid when it commanded it to open. after swapping in another PCM from the junk yard and using the same original PCM programming on my truck. the solenoid worked! that's how I deemed my PCM going bad.

the original PCM would even set the code 78 pointing at the solenoid at fault, but in fact it was good. if you can snag one from the pick a part yard to test, it might be worth a try. might even find out all the old parts you've changed were actually still good.
 
dbrannon79 said:
those electro-digical boxes can do some funky things as they age. my original PCM on my truck I found could not control the wastegate solenoid when it commanded it to open. after swapping in another PCM from the junk yard and using the same original PCM programming on my truck. the solenoid worked! that's how I deemed my PCM going bad.

the original PCM would even set the code 78 pointing at the solenoid at fault, but in fact it was good. if you can snag one from the pick a part yard to test, it might be worth a try. might even find out all the old parts you've changed were actually still good.
Click to expand...
I do have a spare PCM but it is stock, whereas the current has a Heath Tune for the ATT. I got the spare to pass smog in CA. Truck is now registered in Montana and it will stay that way.
 
I have been searching here and there every once an a while for a OEM trans computer and possibly harness to use in my 95 for when I am able to convert to use a DB2 on the cheap. At least cheaper than spending 1k on the aftermarket variety options. Also will have to find a diagram, I'm sure I'll have to make my own harness for parts of the truck for it all to work properly.
 
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