Complete Shutdown at 65mph

[RKTJeep]

Hello, unfortunately i am posting on here sooner than i intended.

 

Tonight i picked up a 1988 MJ Pioneer, 4.0, 4X4, Manual, 114K Miles. About 50 miles into my 100 mile trip home, cruising along at 65mph, the engine completely died. There was no sputter or signs of charging system issues prior to the issue. I put the clutch in while still rolling and the engine did not crank, or have any sign of life. My headlights and dash lights did stay on the entire time. On the side of the highway i attempted to start the engine multiple times, but nothing moved, no sounds from the starter, solenoid, or fuel pump.

 

Now for the history. The previous owner replaced the lock cylinder after someone busted the old one trying to steal the vehicle. He replaced it with a cylinder fromm a S-10 which i believe is a proper fitment.

 

My theory is that there is a loose connection at the ignition switch. This would cause the system to act as though the key is not being turned at all. Unfortunately i am not too familiar with Comanches yet. I plan on checking fuses tomorrow night, then working my way through the wiring.

 

I hoping the knowledge base here will help put me on the right path to sorting out this issue. Nothing like a $250 tow bill introduction into Jeep ownership, Haha. :)

 

 

[HOrnbrod]

The MJ column is a Saginaw steering column, just like the pre-airbag S10 column. Your suspicion that it's an ignition switch problem since you know the history is very plausible. Check the ignition switch connector and harness connector for fried contacts, and align the ignition switch rod are the first things to do.
 

Could be the ignition switch on the steering column or it's connector is fried, or is mis-aligned.
 
Ignition switch, p/n J3250576, available at Rockauto and others. Connector also.


Ignition switch alignment:



Fig. 2: Ignition switch rod positioning
On non-tilt columns:
Move the ignition switch slider to the OFF unlocked position (move the slider all the way down, then back two clicks). The remote rod hole in the ignition switch slider should now be centered.
Insert the remote rod in the ignition switch slider hole and install the ignition switch on the steering column. Tighten the attaching screws to 35 inch lbs. (4 Nm).
On tilt columns:
Insert the ignition key in the lock cylinder and turn the cylinder to the OFF unlocked position.
Move the ignition switch downward to eliminate any slack and tighten the attaching screws to 35 inch lbs. (4 Nm).
Install any components removed for switch access.

 

[RKTJeep]

Thanks Don, this is what I was looking for.

 

Does anyone have a schematic for the ignition wiring harness? I'd like to do some continuity testing prior to dropping the steering column.

[HOrnbrod]

Download the 88 electrical manual HERE.

[87MJTIM]

I suggest test the CPS.  See Cruiser's Tips for Renix engines.

[RKTJeep]

I found the problem.

 

One of the fusible link wires has disconnected from the distribution block. It is a green to red link. What is the best way to replace the fusible link? I might have enough wire to solder it to another piece of wire and put a new eyelet on the terminal. Suggestions?

 

 

[HOrnbrod]

Is it burned off from a short or just old age? If just rotten, I'd replace it with an aftermarket FL in the appropriate gauge.

 

http://www.summitracing.com/search/part-type/fusible-links

 

If from a short, you need to find the cause. What circuit is it in?

[Gene]

Looks like it flexed itself to death, I'll bet the new one will do fine!

 

Gene

[RKTJeep]

Yes it fatigued. I don't see any signs of overheating or melting of the insulation. Thanks for your help guys.