I picked up this dump truck about two months ago and it has an occasional No start / no spark. If I let it sit for a few days it'll be very reliable with lots of trips to the quarry for gravel. I replaced the plugs and wires/cap and that didn't do anything. I tested the coil and it tested fine so I ordered a new ICM. A couple days went by and the new motorcraft (grey) ICM came and I tried to start the truck before I did anything and it started right up. Swapped in the new ICM and No Start. Let it sit overnight and still nothing, so I pulled out the Diode under the fuse block and re-inserted it then tried to start it and it started right up. I put the old ICM back in and it started right up. So now I'm super confused and can't seem to pin down a cause.

I've read about the black ICM and may have to make a trip to the local yard, but would this cause the no start issue?

I would love some input








These two connectors are always coming unplugged but when I have a No Start they don't seem to matter.

 

You need the black ICM, gray module is the wrong one so waste of time to use it return it for a exchange.

Where is the heat sink for its ICM?

Even the fender mounted module requires a heat sink and if it was missing before you bought the truck? that might explain your issue.

I've never had one nore seen a case where a remote mounted ICM failed, that is those properly installed on a heatsink anyway.

Would look like this,



Overheating without it would cause the issue you describe, loss of spark until cools or at least would do so until it no longer functions due to overheating.

Requires fresh thermo paste between the module and heatsink. Both matting surfaces smooth clean and dry and new module should include it in the box.

 

Thanks dan,

The truck had the grey ICM just like in my photo when I bought it. I also noticed on a 20 mile trip the temp gauge was flicking back and forth between reading zero then reading the actual temp, then back to zero. This could be a heating issue too.

So would you recommend a trip to the junk yard and look for a black ICM with heatsink?



Shawn

 

If it is low of coolant then yea, heat would shift from cold to warm/hot as air and fluid passed by the sending unit.
If its full of coolant then there is a bad connection between the sending unit and the temp gauge.

Excessive under hood temps due to low coolant would exacerbate problems with the ICM, especially one with no heatsink on it.
Inner wall of the fender gets hot from a near or overheating engine under the hood the ICM in direct contact with it quickly overheats.

Yea I'd visit a bone yard pick up a heatsink with a black ICM mounted to it, if cheap enough grab a couple of them.

Buying "used" you'll want to separate the two to apply fresh paste between them, depending on conditions and what is likely original its probably dry/hard/dust useless now.

Heat Sink Compound at AutoZone.com - Best Heat Sink Compound Products for Cars, Trucks & SUVS

It takes a special thin wall tool to remove the ICM from the heatsink, I'd pick one up and some fresh ICM paste on the way to the bone yard. So you can make sure the bolts come out without issue, two dissimilar metals come into play with those bolts, small and can tend to snap rather than spin after being in place for years.

The one I have looks like this but there are many styles,



I like it because you can spin it by hand or use a wrench when space is limited, also includes a 1/4" square drive for use with ratchet.

Amazon.com: Ford module tool

 

Thanks for the tips.

Do you know a range of years and models I should be looking for at the yard?

Also, there is often a puddle of bright green coolant on the top of the engine, so levels were a little low. Most of my trips are to the quarry ~ 5 miles away so the truck has not been overheating. It's nice when things start to make sense.

You can also see the outline of what I'm assuming was the original heatsink near where the current ICM is mounted.

I also forgot to mention the truck was a former U-haul and has 215k on it. It's a beast and I'm very glad I bought it.








Shawn

 

If you take a black one from any 94-96 (97HD) model it would be correct for your truck.

Temp sending unit is located right here behind the thermostat housing where the top radiator hose connects to the engine, the single wire plugged into the top of the sensor with the green corrosion showing on it's wrench boss.

Pull that connector off (its a push on style connection), make sure its connection is clean and snug.

Grounding that wire to the engine block with the key in the "run" position should make the temp gauge peg full "hot".

Sometimes they end up fitting loose, if so lightly pinch the connector with a pair of pliers to make it fit tight again. No need to over do it, just pinch it a little if necessary until it pushes down on the post with a little bit of resistance.

And then naturally make sure you keep it full of coolant until fix any leaks you find.

Leak you have now might just be a hose, a loose clamp or it might be the timing chain cover leaking from the coolant passages running through it. Not uncommon for that to happen with em but a fairly simple fix when it does.

 

Check out what I scored today at the local pull and pay. This came out of a beautiful 1995 F-150 XL.



The truck has been running, but I swapped in this new ICM and heatsink and it's still running fine. Hopefully this will solve my occasional no start issue!

Thanks again,


Shawn

 

Nice score, but do yourself a favor....remove that ICM, clean out the dried up heat sink compound, then apply some new.

 

Ahhhhhh

I drove the truck around 30 minutes, dumped a load of dirt and drove it home yesterday. Now today it won't start. This is exactly what it was doing before...

So, I'm wondering if the PCM wasn't the issue. I am glad to get the correct one in there though.

Any other thoughts on what might be causing this intermittent no start?

Thanks,

- Shawn

 

The two items that normally cause this are the PIP sensor and the PCM Computer.
The next time you have no spark pull the SPOUT shorting bar jumper out and see if spark returns.

If it does then it points to the PCM computer.

If spark does not return then it points to the PIP sensor.
In very rare cases it could also be the Ignition coil or the Ignition switch or its plug.

 

Thanks for the tip, but I don't quite know what the spout shoring bar jumper is. I'm still pretty new to working on this big truck.

- Shawn

 

In post #5 above it is the gray thingy hanging down in the second photo.


/

 

Okay - That I can do. I tried to start the truck just now...no start. I pulled out that gray thing and it started right up. I replaced the gray thing and it started right up.

I also noticed a connector that was unplugged right there by the PCM (edit:ICM):



Thanks for the help,

- Shawn

 

The single wire is the STI wire.
You ground that wire and turn on the key to start the self-test.

 

Thanks. There are several other loose connectors in that area and I figured they were for diagnostics. The truck is a 1996 but does not have an OBDII connector.

So, where should I go from here? Is it appropriate to use this trick to get the truck started, or can I drive it with the spout removed? Should I try to replace the ICM again?

Thanks,

- Shawn