I'm Stumped

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Matthew T

Matthew T

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OK, after a weekend of working "real estate broker", I'm back at it today for a few hours. ***** getting real, hooked up my battery charger on 100 amp starting boost. Guess what, no theft light flashing and the vehicle will start. It does die right away but, I now really think I have a short or ground fault in the circuit that communicates and powers (pats to pcm and ignition). I got a good whiff of electrical smoke from the drivers side of the vehicle under the door/front fender. Reset charger to 6 amp to top it off it's dropped .5 volts over 2 days sitting. Any suggestions appreciated.
 
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Matthew T

Matthew T

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Update, I removed the GEM/CTM modules and inspected for moisture or other damage. None present, so I checked all fuses and relays. Again everything checked out fine. Cleaned and applied dielectric grease to everything. Now that the GEM/CTM modules are out of the vehicle I will be checking ground circuits and giving the wiring a thorough once over. The GEM/CTM is a complete ***** to remove. However if you remove the side kick panel and remove the dash frame bolt, you can flex that frame a little to create enough room to make it a lot easier.
 

stamp11127

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The engine bay harnesses connect to the internal harnesses at the bottom of the driver side footwell / firewall. I would check those to see if any wires have burnt. They are a real pain to get to unless you're skinny.
 
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Matthew T

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Yeah, that's my next move. I reinstalled the GEM/CTM took the battery down to the parts store to have it load tested (it's fine). Cleaned the terminals and whatnot, and the darn thing started and ran. The idle is still wonky but the damn thing runs now. I was noticing those connectors at the bottom of the kick panel and will be cleaning all those up before I put all the kick panels back in. Ran for 10 minutes on its own with no codes present. Some of the connections for the CTM were pretty ugly. I think the 20 factory grease was cooked on pretty good.
 
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Matthew T

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It lives!!!!! OK, I've got this Expedition running real nice now, here is what I think the problems were and how I solved them. At first glance the crank/no start with no codes issued made the vehicle appear to have a bad fuel pump. I replaced it and was totally wrong, I didn't notice the PATs issue (flashing theft light that would go on for 15 minutes) and should have. So after throwing that part at it and deciding that at 213k miles it was a liability anyway, I started down the path of PATs, PCM, GEM/CTM or grounding issues. I checked every fuse, link and relay in those circuits, I removed and bench inspected/tested the PCM, PATs Module, PATs antenna, and GEM/CTM modules reading every manual and diagram I could get my hands on. No problems with any of those modules. The vehicle would start and run while being jumped or boosted. Battery checked out within specs and the only thing I could think of was an open ground, because the charger/booster and jumping vehicle were both grounded properly. New neg battery cable, two new ground wires and every ground I could find inspected, cleaned, greased, put back together and a squirt of paint. After I got it running I replaced the air filter and cleaned the throttle body. What did I learn? Any future PATs or PCM concerns will be addressed with a grounding system inspection first. My total parts and consumables with this saga was just under $200. I guess I spent 16-20 hrs all total on the repairs. The fuel pump quotes alone were all at $800. I think the electrical diagnosis and repairs would have at least doubled that bill. Thanks to everyone who helped with advise and encouragement.
 

1955moose

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So it turned out to be a bad ground or 2. Look at the education you got! Glad you figured it out, knew you would.

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Matthew T

Matthew T

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Yeah, negative battery cable, engine to body and body to chassis required repair or replacement. I cleaned up all the other ones I could find. Runs nicer than it has in a year.
 

JOlsen

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I had a similar issue when my inertia switch shit out on my 99. Maybe check that.

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