My 02 Discovery will not start. There is power in the key on postion but does nothing in the crank position. I have tested for power out of the ignition switch and is all there to the ignition relay and beyond. I have checked the wiring from the stater motor relay back to the BCM and the wires are good. I do not have ground at the starter motor relay. If I provide ground to the relay via jumper wire it will start and run fine no warning lights. What could be the problem? what can I check to narrow this down to get fixed. I don't want to have to take to dealer and remortgage my house. I am desperate to get this fixed so I can go on an overland adventure. Please Help!!! DiscoMike do you have an answer?

 

Looks like ground for the relay comes from the BCU (body control unit) if I'm reading the diagram correctly. Is there any chance you truck thinks the alarm is still set? Are you locking and unlocking with the plip or the key?

 

I am unlocking with the key. The fob has never worked since I have had it. The alarm arms and disarms with the key in the drivers door just fine. The security light blinks.

 

Is this affected by weather temps at all? What voltage is your voltmeter reading at the starter terminal with the key on? I am gonna guess grounding problem since you were able to jump it.

Wiring goes:

+ Battery

50A fusible link (under bonnet)

Inside Fuse Box

Ignition Switch

10A fuse (Inside Fuse Box)

Starter Relay

BCU

Ground

 

Sloan74. I checked all the grounds are good. Cleaned them while I was checking them. The ground signal to the stater motor relay is not present. That is supplied by the BCM. The BCM is not sending it out. What is cause this? I have jumped ground from the negative battery terminal and it starts and runs fine. Any suggestions I will try. Anyone?

 

When you checked your grounds did you clean and reclamp your negative battery post? and from there the negative connection to the block? (the BCM may not be showing a ground because it doesn't have a path to one. Ground is relative.)

 

Jabez. I cleaned and check the ground to the block and the terminal. The ground to frame and the connection at the fender were all cleaned and checked.

 

Just to make sure, the security light is NOT blinking while you are attempting to start it?

 

No the security light does not blink.

 

I understand you checked all the grounds. At this point all I can say is that I have personal experience myself and vicariously through others with poor (not bad) grounds preventing the starter to pick up (even after I have cleaned them) (multiple times through the years...)

Anyway, one other thing I have seen is the key switch is bad and not making contact in the start position. You can probably do a continuity check on that if you look at a wiring diagram. (just make sure to disconnect the battery when you do a continuity check.)

If your key contacts are closing I would replace the battery ground cables before I assumed it was the BCM. They get old and brittle.

Just some suggestions.