Truck won't start or crank

[juddspaintballs]

Yeah, I'm really hoping it's the switch and not the wiring. I hate tracing that stuff down and fixing it.

[Glagulator]

May help 99_65tdStartCir.pdf

[juddspaintballs]

It's not the ignition switch. I just spent the last 2.5 hours putting a new one in. What a waste of time and money.

What else could it be?

[juddspaintballs]

I'm still confused why I get power at pin 86 with the key in the RUN position and not just START and also why I have continuity with ground on pin 86 and not pin 85. If I manually ground pin 85 and turn the key to RUN (or START), the starter cranks but the engine never starts.

I'm almost at the point of taking it to a mechanic. They're going to spend several hours doing what I've already done, tell me that the starter is bad, the ignition switch it bad, etc. and charge me out the ass to do everything I've already done only to spend hours figuring out what the problem could be.

[racer55]

Having power on pin 86 in run and start tells me that there is a short to power in the wire from pin 86-melted together wires likely.

And pin 85 should be a ground.

[JMJNet]

Have you taken the starter out and have it tested by a starter shop?

[juddspaintballs]

Looks like I'll start tracing wiring on Thanksgiving since I work tomorrow.

It appears I need to follow the yellow wire from the ignition switch to the fuse block in the dash first. If I remove that 10A crank fuse and test there to see if the wire gets 12v when in RUN, then the problem is between the fuse block and the ignition switch. If I only get 12v when in START, I need to move on to the purple wire going to the neutral safety switch.

If I unplug the switch at the transmission I can test purple wire to see if it only gets 12v when the ignition is in START or if it's also 12v when in RUN. If it's only powered under START, then the problem must be in the purple/white wire going to pin 86 for the starter relay in the fuse relay center.

I'm going to take a stab in the dark here and say it's probably going to be an underhood wiring issue simply because I have no ground on pin 85, pin 86 does have continuity to ground (weird), pin 86 is always 12v in RUN or START. Pin 85 gets 12v via the relay whenever the relay is in place and the key is in RUN or START.

[racer55]

Pin 86 should have continuity to ground because it will flow power from pin 86,through the starter solenoid coil and then to ground.

[Glagulator]

PIN 30 CONNECTS TO M6 (IGN A FUSE) (RED WIRE ONLY UNDER FUSE CENTER)
PIN 85 GROUNDS TO G105 THRU SPLICES S107 & S147
G105- CYL #7 INTAKE BOLT
S107- ENG. HARNESS APPROX 15" FROM EBCM BREAKOUT TOWARD TRANS HARNESS BREAKOUT
EBCM = ELECTRONIC BRAKE CONTROL MODULE
S147- ENG. HARNESS APPROX 1.5" FROM STARTER SOL. BREAKOUT
PIN 87 CONNECTS TO STARTER SOL. (PPL)
PIN 86 CONNECTS TO TRANS RANGE SWITCH (PPL/WHT) ON TRANS
THEN BACK TO BULKHEAD CONN. (PPL) C100 POS E1
THEN FROM C100 TO CRANK FUSE #8 (PPL) or (YEL) BOTTOM RT HAND WIRE FROM INSIDE
THEN TO IGN SWITCH (YEL)

Racer55 is probably right about a short.
Put your test light on pin 86, turn key to run, start pulling one fuse at a time and replacing them
till one kills the light. IGN A feeds the starter relay and the starter solenoid and many other items
in the run position so it may be the only one that kills power, but most of the circuits from the run
position are fused and maybe you will find the culprit. This will indicate which circuit the short is
on and should help narrow down the search.

[juddspaintballs]

I just ran outside and checked the 10A crank fuse in the dash because it was easy to get to. I have 12v from the yellow wire to the crank fuse position only when the key is in START. No power when the key is in RUN. That's a good sign that at least from the ignition to that fuse, everything is as it should be.

Thanks for the information Glagulator. I will probably not get a chance to touch this again until Thursday evening. I'm suspecting the problem is going to be just under the fuse relay center or in the close vicinity.