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My 1996 F150 gives a 0500 code. plus fuse #18 in mini panel on drivers side dash blows. I'm trying to find the transmission control module. but my Ford repair manual is not very clear on where it or it's conn are located! Any and all help is welcome and appreciated!!!
The transmission is controlled by the Powertrain Control Module (PCM). This computer controls the engine and the electronic controlled transmission in your truck.
The root cause for your P0500 code is the blown Fuse 18. It supplies power to the PSOM, which in turn provides a usabe Vehicle Speed Sensor (VSS) signal to the PCM.
Fuse 18 supplies power to the PSOM, Electronic 4x4 shift control, Air Bag Diagnostic Module and the Shift Interlock (prevents the shifter from coming out of park unless your foot is on the brake).
After studying the shop manual, (DUH)! I learned that the TCM only applies to 4wd!!!! SO--- on to more trouble shooting.
1) Short has been fixed. Have a bad Airbag Diagnostic Monitor mod. Internal cap is dead short.
2) Have Batt volt to PSOM.
3) Have Run volt ts PSoM.
4) Have correct mi indicated on odometer.
5) ALL lights, gauges work properly.
6) I have no way measure VSS.
7) Truck starts, shifts from park to any gear. (No ADM installed, instrument cluster uninstalled)
I may have given more info than needed, but it gets rid of a mild case of FRUSTRATION!!!!
All this to say, how do I know if the PSOM is A.O.K. and what's next?
If you have a Digital Voltmeter you can measure the VSS signal:
CHECK SPEED INPUT SIGNAL
NOTE: Only wiring harness end of connector is to be probed.
* Connect Rotunda Digital Volt-Ohmmeter 014-00407 or equivalent to Pin 4 (speed in ) and Pin 5 (speed in -).
* Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)?
OR:
* If available, a frequency counter may be connected to Pin 4 (Speed in ) and Pin 5 (Speed in -).
* Does the displayed frequency of the signal increase smoothly and continuously from 0 to approximately 667 Hz at approximately 48 km/h (30 mph)?
OR:
* If neither a voltmeter nor frequency counter is available, vehicle speed control may be used as a good indicator. If it works normally, then the speedometer module is at least receiving a speed input signal and the wiring and sensor can be assumed to be good.
Rear axle sensor should read 800-1400 Ohms across the pins, and more than 10 Ohms from the metal shell to either pin.
I did as you instructed and the voltage did as you said! Used an ancient Simpson 260 to measure.
I'l be buying both a ADM mod and a PSOM.
I'll poston repair results.
Score another one for this sight's members!!!
Many thanks!
Before spending some coin on a PSOM pull yours out then inspect for signs of broken or loose components as well as the ever prevalent leaking capacitors. You might get lucky with a simple fix.
Before spending some coin on a PSOM pull yours out then inspect for signs of broken or loose components as well as the ever prevalent leaking capacitors. You might get lucky with a simple fix.
I have no way measure VSS.
7) Truck starts, shifts from park to any gear. (No ADM installed, instrument cluster uninstalled)
And hello from North Port!
I just wanted to clarify something... are you having the hard shifts with the instrument cluster removed? If so that is the reason. The PSOM is on the back of the cluster, and is needed to supply the PCM with usable speed data. Without it you will get hard shifts.
To update my post----- I found the root problem and fixed it!
I'll make it short as I can. It was a bad ORIGINAL connector on diff that was giving good readings at all the wrong times!!!!! But, somewhere along the way, the PSOM failed. Replaced conn. and PSOM and all is well(esp my good old truck). MUST: use dielectric grease on ALL electrical connectors!!!!!
The short blowing fuse #18 was for the airbag diagnostic module and some other functions. Removed bad ADM and found internal cap shorted--I,ll replace it soon.
Then to top it all off, my A/C would not switch to MAX AIR. Replaced several vacuum line conn and one more problem solved! Once again- thanks to all members for their input!!!!!!