Check diagrams above. I added one I left out (thought it was only for Excursion). It might be the most important one.

Book says transfer case shift relays are "LH side of engine compartment, next to battery junction box". So you are looking for the ones you have labeled 40 and 41.

 

So no power at the plug in the first picture in any drive configuration ie the 4x4 switch in ny position. Measures 0V, also measures 0 ohms (incase that could be important)





I have two sets of two relays. But the boxes are very slightly different. The one where I left the relays out have no clip in the centre, where as the others do - hoping this will help identify which are the 4x4 relays - I'm thinking the front ones that I left in.




Front of truck to bottom of pic

So measuring across the relay posts on either of the front two, with ignition off, there is 12.8V. Measuring across the set where the relays are missing in the picture there's 5.6V and 8.5V ignition off.

I cleaned up all the contacts with contact cleaner as they were pretty dirty. I'm not sure where to go from here, or what the voltages I just posted tell me, other than I'm getting no power at the plug on the TC so the problem is further up the line.

https://www.ford-trucks.com/forums/8...se-relays.html This thread leads me to believe that the relays for the TC are the two in the pic I left in. I'm wondering if I should just change them out for new and see what happens? I read a post where someone mentioned they were standard bosch - have found them by duralast at Autozone 16$

Ford part #:
F0AB-14B192-AA
AutoZone part #:
Duralast 19273
Santech MT0532
O'reilly part #:
BWD R3177
Other part #:
STANDARD MOTOR PRODUCTS RY116

How do I test the actual switch?
Does the voltage at the relays give any indication of the GEM state - FUBAR or no?

 

The switch on the dash is the last thing you would look at. I am going to post the operational checks from the book for you tomorrow. I am at work now and don't have the books with me. Once you get to a point in the op checks that fail, it should point you to the correct place in the troubleshooting matrix. Either that, or get a code reader that can read the GEM module.

Check the wires coming into the relays. Look for the colors that correspond to the diagrams.

Then go here: http://easyautodiagnostics.com/misc-...-bench-tests-1

 

Thanks again Mike, I'd come across the bench test yesterday - looks simple enough I think, I'll try it today!

 

One other point, don't know if its relevant or not, the left hand section of my dash lights are out. It looks like just one lamp as the fuel pressure and battery voltage aren't fully illuminated.

 

It's not relevant, but it means you're due to pull the dash and replace all the bulbs.

 

Thanks Tugly

 

Bench tested both relays and they are good.

I had limited time so was only able to then pull the switch and test it. No time to pull the GEM yet.

But what I did find was that with the 4 connectors on the back of the switch I could only get continuity on the two outside connectors regardless of switch position. I did get 1100 something ohms on the middle two tabs switch at 4H, and 360ish ohms with switch in 4L and 3300 ohms in 2H so im assuming switch is good.

Also tested the plug to the switch got 11.5V across what i think is 1&2 and 2&3 which i think corresponds with the wiring diagram. If that's correct, I believe the problem lies between the relays and the switch I guess???

I should add that when turning the switch to the various positions the relays are not heard to click.

 

So relays are not being energized when commanded to...

 

I may also pull the GEM tomorrow - any hints or tricks?

 

That is correct

 

Here are the complete operational checks for your system:




























The first 3 steps are to establish baseline conditions. C4 is where it gets to the meat of it. Don't skip the first few steps, though.

 

Thanks heaps for this. I'm at the end of C5 with a need to check the GEM DTC's. Anyone aware what fords current going rate is for this? I'm guessing the usual Autozone/Oreilly analysers aren't going to cut it?

 

I'm pretty sure AE will read it. Where in CO are you? may be someone near that will help.

 

I appreciate the offer! But I'm skulking round Galveston TX currently.