2000 Ford Explorer will not start after replacing both speed sensors on the 4WD Transfer Case

[JohnG1771]

After completing the brown wire Brown Wire Switch Modification to disable the Automatic 4WD (front binding on turns in Auto), I ran the vehicle as a actual 2WD (disabled clutch coil in transfer case Borg 44-05). I decided to change the speed sensors to fix the original problem causing the front wheels to engage in Auto.

I installed the 2 new speed sensors per Washington Ford Parts department (part numbers below) & now my 2000 Ford Explorer will not start. I have fuel pressure and 12V at the coil pack but PCM not making spark. Checked all fuses related to the GEM module (see print) and they are good. Currently the transfer case main plug is unplugged but it still will not start. I double checked the wiring at the main plug (sensors & shift motor) & it is correct. The GEM module still works everything else (radio, power window, locks, adjusting mirrors). I tried disconnecting the battery over night to reset any faults on the GEM (No faults on the PCM - using Actron CP9580 scanner) but still will not start. Could the parts be wrong/bad and I fried my PCM? Can the GEM module stop the PCM from starting? Attached is the parts diagram (with my VIN Number) the Ford Parts department sent me last week and the electrical diagram. The car ran fine before I replaced the sensors. Any help will be greatly appreciated.

1L2Z-7F293-AB (Blue wire) vehicle speed sensor (VSS), Motorcraft# SW-5645, on rear of transfer case by fill the plug (item 32 on Borg 4405 Print).

1L2Z-7F293-BA (Black/Green wire) sensor by Transfer Case Shift Motor, Motorcraft# SW-5644 (item 53 on Borg 4405 Print).



Thanks

 

[J_C]

John and I have discussed this a little in a private conversation, where I was suspecting it might not be getting the crankshaft sensor signal, due to sensor itself failing, dirty reluctor ring, bad wiring/connector, or finally a bad PCM.

 

[JohnG1771]

I replaced the crank shaft position sensor last night & disconnected the battery to reset both PCM & GEM over night. Plugged the main plug back in at the transfer case before reconnecting the battery. I then turned the key on (not to the start position), pressed the brake peddle, & cycled the 4WD from Auto to High to Low & back to Auto so the GEM would find its position. The car started & the previous 2V peak to peak sinusoidal crank shaft position signal went off the chart. I thought I was good so I turned it off closed the hood & cleaned up. I then went to remove the car from my garage & it would not start. I opened the hood, checked all fuses - ok, repeated the 4WD position switch cycle & it started. I drove it out the door & noticed front wheels binding while turning in my driveway. I then flipped the toggle switch, I inserted previously to disengage the transfer case clutch removing the clutch from the circuit, & the car shut off & would not re-start. I then pulled the fuel pump relay to recheck for spark & feedback from the new crank shaft position sensor. No spark and back to the previous 2V peak to peak sinusoidal crank shaft position signal. Rang out the crank shaft position sensor plug back to PCM pins 20 & 21 which were good. I then disconnected the battery to clear any faults in the GEM & PCM. After a half hour my cousin showed up with a good scan tool to check faults on the GEM. The car started again and he cleared about 12 different faults which did not come back. However, the car shut off after about 1 minute. It then started right back up. It did this 3 or 4 times while he monitored for faults. Then it stopped and would not start again. After running a few test sequences using his scan tool it started again and continued to run without ever shutting off again. He had me unplug the Cam Position Sensor to show me the car would continue to run since it only needs this signal to start. Thus the Cam Position Sensor was not my problem causing the car to just shut off on its own and leave no faults. He suspects the problem could still be with the new crank shaft position sensor or a relay dropping out. We did swap Relay 4 (PCM power relay) with Relay 9 (Blower motor relay) while troubleshooting but it still did not start at that time. Also while the car was running, we banged on the fuse box under the hood & wiggled the PCM connector trying to get the car to shut off . The car would not shut off. I just got back from running the car for at least a half hour to enable the PCM adaptive learning and it is running fine. I left my brown wire clutch disable switch in the off position eliminating the automatic 4WD. My cousin owns a transmission shop and said I will still have 4WD and the clutch is only used in auto. At this point, I plan on running the car as is with the automatic 4WD disabled. Finally, he said if the problem comes back that I should perhaps buy a better crank shaft position sensor. The new one is a Duralast SU2032. The original sensor was covered in oil & dirt and rings out at 380 ohms while the new one is 468 ohms. If it acts up again, I may clean up the original and re-install it. Any thoughts on what was causing my issue ? Any suggestions on what to do next if the problem returns? Any advice would be greatly appreciated. I will let you know if the problem returns.


Thanks