All Gear Starts MLPS Neutral Safety Switch help

[rjm65]

Vital stats for this truck are 1993 F-350 XL, 4X4, Crew, SRW, 7.3 IDI, E4OD, 1356, 10.25

My truck will start in all gears P-R-N-D-2-1. I have purchased and correctly installed a new MLPS nuetral safety switch and no change. Even with the MLPS plug connector completely disconnected from the switch and hanging in the air under the truck, the vehicle will still start in any gear. Most people write about a no start situation with the MLPS. Mine starts anytime and not even hooked up. What might the previous owner have bypassed or re-wired on the starting circuit to make this happen?

I really need to put things right because I just rebuilt the transmission with hard parts, but I don't want to use the truck at all with known electrical issues. I am getting the OD light blinking on the shifter for limp mode and no reverse lights, but I had this even before rebuilding the tranny. Speedometer and tachometer work correctly. Thanks in advance for any advice you can give.

rjm65

 

[gdhillon]

I'm just going out on a limb here but did you check your neutral safety switch wiring to your gear lever and tranny? Or whatever it connects to

Just curious, Does it "jump" when you start it in gear like manuals do?

 

[rjm65]

The wire harness from the smaller 60 pin computer on the firewall driver's side to the MLPS connector plug at the transmission looks uncut and in it's original plastic loom, so I'm guessing it hasn't been tampered with or spliced there. I am wondering now if something was done under the dash because I read online about a neutral clutch jumper that is installed on all manual and automatic transmissions just after the ignition switch, but can't find it under the dash. Supposedly a red wire with blue stripe (which I do see on the solenoid on the pass fender engine compartment) but can't find the same wire under the dash. And yes, the truck does jump when I hit the ignition key to start in R-D-2-1. Could something have been done to the ignition switch itself to override the MLPS?

 

[gdhillon]

hmm. Well on my truck (manual) the clutch safety switch was around the mc rod. And the wire loom came down (4wires) to a grey connector dohicky that attached to the clutch safety switch.
So anyway theres 4 wires two are green (i think i dont quite remember) and the two that are red with blue stripes are the ones that need to be cut, stripped and soldered/taped/crimped together. I used one of those blue butt connectors I think they are called. However, yours is an auto so I would assume that there is no mc rod? and theres some different type of linkage going on for it attach to the tranny. My wire is under the dash above the pedals. I think yours would be in a different location though b/c yours is auto. I will get you a picture of mine if you'd like.

Did you use the mlps adjusting tool haynes says to use?

Maybe it is worth it to take the ignition tumbler out and check it out? (Ihear thats quite the job though)

 

[rjm65]

Thanks for the tip, I'll be looking for those wires under the dash tomorrow and probably pull the covers on the steering column to see the ignition connection. From what I've read on the net, even the auto trucks have the neutral jumper switch installed, just that the autos have a dummy plug to complete the circuit in the absence of a clutch pedal assembly. The confusing part is that everywhere I look for signs of tampering on the wires looks original and factory like it's never been touched. I would guess that the steering column has been opened before because the covers aren't straight and the actual ignition switch does work but pretty loose.

I do not have any special tools to do the MLPS neutral safety switch installation, but it's pretty straight forward: truck in neutral, alignment marks on the switch perfectly lined up for N. The truck will start without the switch even being installed with the connector plug off, and the starting circuit diagram shows this as a part of completing the loop for ignition. I even pulled the TECA relay out of the power distribution box under the hood and the truck still starts in any gear.

Thanks for your continued help.