So I've got an issue with the starting circuit on my 93 F150 with the E4OD. I've searched and searched, found lots of good info, but I'm still in the dark on how to solve my problem.

Yesterday I stopped in town, and when I went to start the truck it would click (relay working) but wouldn't activate the starter motor. I Jumped the leads on the starter and brought it home. Once in the garage it was a simple matter of one of the leads had fallen loose. I reconnected it, and while I had booked a few hours free from kid duty and this had only taken a few moments to fix, I decided to enjoy my garage time and tackle another issue involving the gear selector needing to be jammed past park for the key to release.

I readjusted the shift cable at the tranny and tightened the torx bolts securing the shift rod to the steering column. This didn't help my issue, so I pulled the shift rod off of the column entirely and saw that there is a locking tab that pops up into the shift rod when in park and it was just not quite seating itself. I ground a very small amount off the shift rod and reinstalled, and now the park lock / key release works wonderfully. i realigned the indicator on the dash, reassembled and was quite pleased with myself. Of course, when I hooked the battery back up and went to start the truck… nothing.

All electrical accessories work, but when I turn the key I don't even get the click from the relay. Theres a soft click from somewhere (not the relay), but nothing further. I jumped the relay and the truck fired up, so at least I know my original problem was fixed.

In trouble shooting, I took a look at all electrical connections in the column and all looks fine. I readjusted the MLPS at the tranny, aligning the neutral marks, and no love there. I do have back up lights when in reverse, but I haven't looked further at the MLPS. I'm not sure why it would not function today when it was functioning yesterday?

So I am asking for your help… what am I missing? Is there something else to check? I figure the problem is between the ignition switch to relay, but what might I have inadvertently messed up? Any suggestions are appreciated.

 

Start with the starter relay itself. Ttake the small wire off the relay and have someone turn the key as if starting the truck (it won't start with the wire off). With the person turning the key, test for voltage on that small wire. If that has voltage then you are getting a signal from the ignition switch to the relay. Maybe replace the relay, they are pretty cheap.

With that all sorted out, maybe replace the MPLS. I have had some go bad and nothing I could go would fix it other than replace it.

Post back your results

 

Just checked for voltage at the wire to the relay with someone trying to start the truck and no reading. I'm thinking it has to be something in the mpls. I think I'm going to pull that unit and test it. I'll let you know how that goes...

 

Ok, so checked the resistance of the MLPS against these noted expected values...

P 3769 to 4608 ohms
R 1304 to 1593 ohms
N 660 to 807 ohms
D .... 361 to 442 ohms
2 190 to 232 ohms
I 80 to 95 ohms

and mine checked out in the correct range for all positions. So… ???

 

If this were me, I'd start going backwards from the wire you removed from the starter relay (starter solenoid). Maybe there is a break in the wire that sometimes it touches? Maybe there's a problem at the ignition switch in that wire doesn't always touch the contacts when the key is turned? I don't know if there is something else that would prevent this wire from getting power when someone turns the key and tries to start the motor. That wire goes from the solenoid on the passenger side of the truck, through the wiring harness going back to the driver's side in front of the radiator. From there the harness goes along the driver's side fender and this wire goes into a large connector (I don't remember how many pins this large connector has, 72 or 84...something like that). This large connector is to the left of the PCM (as if you were standing in front of the truck looking at the headlights) and it goes through the firewall into the cab. From there it goes to the ignition switch.

 

Ok, so I started following the wires... Since I knew there was no power coming from the ignition to the relay, I traced that red blue wire back through the truck. Eventually I got to the steering column where I found big red blue wire. Gave it a slight tug and the entire main connector came free. It is secured with a bolt which had come loose somehow, and in my shift linkage dealings I had managed to kick it just free enough to disengage that red blue wire, but nothing else. At least now I have a good grasp on the starting / shifting mechanisms of the f150.

Thanks for your help, guys. It is appreciated. I'm finding a lot if small issues with this truck, so as I get stuck again I'm sure I'll be back!