Ive got a 2000 v10 f250 with the ESOF system. Here's my issue, it will engage into 4x4 no problem, but just wont switch to low range. I know the brake switch works and that you have to put the tranny in neutral with brake pressed hard for it to engage. The relays under the hood are in working order. Already checked those. What else could it be? Maybe a bad GEM module? How can i test the GEM, Any input is greatly appreciated.

 

Try getting the truck rolling slowly, then put it in neutral and press the brakes just hard enough to light up the brake lights. Then turn the switch and see if that works.

 

Sorry forgot to mention I've tried that method with no luck at all. Will play with it again but almost sure its something else. But thanks for the info!

 

I have heard inconsistent information on this. On my truck, and according to the wiring diagram on your truck, you have a 5 wire Brake Pedal Position sensor. I have heard people with 2000's tell me that they only have a two wire BPP. The BPP is on the brake pedal arm where it meets the plunger for the master cylinder.

Buy anyway. IF you have a 5 wire BPP, it is basically two switches in one. The 3 wire double throw switch tells all the electronic modules (PCM, GEM, ABS, Cruise Control, etc) if you are pressing the brake, so they can act accordingly. The other 2 wires are a single throw switch that just activates the brake lights.

I had a situation where the 3 wire switch failed, but the 2 wire switch did not. In my situation, I noticed that it took significantly more brake pressure to deactivate the cruise control. But I'm sure that it wouldn't have gone into 4Low either, because the GEM didn't know the brake pedal was pressed. However my brake lights still worked.

Try this. First, get up under the dash and look at the BPP and see how many wires it has. If it is a 5 wire BPP, then tell us how well your Cruise Control works. It should take a tiny amount of pressure on the brake pedal to disengage it. If it takes more, your BPP may be bad.

I've attached a wiring diagram that shows the BPP that may make it all make more sense.

 

Found what u were talking about, I have the 5 wire plug. Here's the thing, cc not working, have a busted clock spring so horn an cc not working right now. But seemed to work just fine from what I remember, clock spring been out for almost 2 months now. Have part just waiting to get puller from buddy of mine.

 

I would say the most likely problem (for the 4Low issue) is that the BPP is bad. You could test it with a DVOM, pin 2 should be grounded when the pedal is not pressed and should have 12V when the pedal is pressed.

On my BPP, the numbers molded into the switch itself were the opposite of the numbers in the diagram. I don't know why. You would want to look at the wire colors to be certain.

 

My plug has no numbers, can u help out with wire colors?

 

The wire colors are on the diagram.

pin 1 is pink w/ orange stripe
pin 2 is red w/ light green stripe
pin 3 is light blue w/ black stripe
pin 4 is light green
pin 5 is light green w/ red stripe

 

Thanks. An sry didn't see the colors in the diagram. Just finished testing an switch checks out ok. 12vdc when the pedal is depressed. Any other ideas? Going to start looking for a manual transfer case here soon if I can get this electric junk fixed, and thanks again for the help