Cooling fan doesn't turn on, 60A fuse pops immediately

[Chythar]

I tried to get the Cobra clone smogged today, and the bugger overheated before the test finished. The fan never turned on at all. I'm replacing the radiator cap as well, it leaked out the side of the cap long before it over heated. I found the 60A fuse for the cooling fan in the fuse box, and it was popped. Explains why the fan didn't turn on. But when I replaced the fuse and hooked the battery up, the new fuse immediately popped. Not so good.

I have a decent voltmeter (tests amps and ground as well), but I'm not sure how to diagnose this. I did hide the wires in the fenders, so it's entirely possible something is shorted or kinked up. I re-used the CCRM from the wrecked Cobra, so it's also possible it's damaged. Can anyone give any advice how to test my wiring? Randomly guessing would take forever. Do I test resistance along the wires, amps, what?

 

[nunly94gt]

If your looking for a break in the wire, test ohms on it from one end to the other on each wire. One of them is chaffed somewhere and should be easy to find.

 

[HISSIN50]

The fuse will blow even if the engine is cold or the fan is unplugged (to rule out the fan motor seizing)?

I would disconnect the CCRM's elec connector and try installing the fuse. If it doesnt blow, the bk/o wire from the fusebox to the CCRM should be ok.


Some electrical info for the fan

If things are still ok, you could try leaving the E-connector to the CCRM disco'd but plug the fan in. Then jump (with a fused jumper. I've used a 30 amp fuse for burst bench testing) the fan's Common and Normally Open terminals (i.e. IIRC jump pin 3 and 4 to 6 and 7). If this works fine and the fan comes on but the fuse blows with the CCRM plugged in, that would lead one to test the CCRM further.

Do a little testing and post up results and we can go from there. Test things at your own risk, etc etc.

Good luck.

 

[Chythar]

The fuse will blow even if the engine is cold or the fan is unplugged (to rule out the fan motor seizing)?

I would disconnect the CCRM's elec connector and try installing the fuse. If it doesnt blow, the bk/o wire from the fusebox to the CCRM should be ok.

The fuse blows even if the engine is cold. The engine is not running when the fuse blows - as soon as I touch the negative terminal to the battery, the fuse pops.

I'll disconnect the CCRM and try installing a fuse. And stock up on a lot of 60A fuses.

Hmmm, I'm really wondering about the CCRM now. When I first start the Cobra, it turns over but dies immediately. Sometimes the engine starts the second try, but always on the third try. It runs a bit rough for a bit but smooths out after a minute or so. I presumed that this was due to bad gas (the gas is over a year old, though I do have stabilizer in it) or a plugged fuel filter. But the CCRM controls electrical power to the engine, and I believe the fuel pump too. I wonder if all these things are related?

The donor Cobra was in a front end wreck, and the whole area around the Cobra's CCRM was mangled. I think I want to open the CCRM (if possible) and check it out.

Just to state all electrical problems, I also don't have working fog lights. They worked before the engine swap, so the base wiring should be good. (You can get working fog lights on a 94-95 V6 by installing a fog light switch, a fog light relay in the underhood fuse box, and the fog lights themselves. All the wiring is there) The switch in the center console is lit and the fog light relay looks good (I popped the plastic cover off to inspect the internals - nothing visibly fried). I don't know if it's a related or separate issue, but I thought I would mention it.

My horn isn't working either. *does research* According to the fog light electrical diagram, it shares a fuse with the horn. The fuse looked good but I'll replace it anyway.

I will treat the popped fuse as a separate issue from the starting issue, but I believe they all have the CCRM in common. I'll report back tomorrow on my tests.

 

[94-302-vert]

Something is obviously shorted to ground. Disconnect the fan and ohm out the positive lead at the fan connector to ground. Geep doing this up and down the junctions until you find the area that is causing the problems... the positive lead (wire) should always have a high resistance to ground (well above 100 ohms)... should stay on OL...

 

[HISSIN50]

You should find the issue in the wire egressing the fan fuse and going to the CCRM. I'd unplug the CCRM and try another fuse. If it blows immediately, that would support that hypothesis. You might have an easier time running a new wire than trying to find the short. A short finder can kinda help if you do wanna trace it.

Good luck bud.

 

[Chythar]

Looks like I have a short. I unplugged the CCRM, and a new fuse blew immediately upon hooking up the negative terminal - just like before. Joy.

So I'll follow 94-302-vert's suggestion; check the resistance on the positive fan lead to ground, and keep checking back on each connector in the way. Any recommendations on a short finder?

 

[HISSIN50]

Looks like I have a short. I unplugged the CCRM, and a new fuse blew immediately upon hooking up the negative terminal - just like before. Joy.

So I'll follow 94-302-vert's suggestion; check the resistance on the positive fan lead to ground, and keep checking back on each connector in the way. Any recommendations on a short finder?

I still stand behind my previous thoughts. When you disconnected the CCRM, you divorced the fan mtoor from the fused circuit. Thus when the fuse just blew on you this last time, the fan had nothing to do with it.

 

[94-302-vert]

Looks like I have a short. I unplugged the CCRM, and a new fuse blew immediately upon hooking up the negative terminal - just like before. Joy.

So I'll follow 94-302-vert's suggestion; check the resistance on the positive fan lead to ground, and keep checking back on each connector in the way. Any recommendations on a short finder?

This automatically means that the short is somewhere between the fuse and the CCRM. Retrace your wiring and see if it is pinched anywhere.

 

[Chythar]

I still stand behind my previous thoughts. When you disconnected the CCRM, you divorced the fan motor from the fused circuit. Thus when the fuse just blew on you this last time, the fan had nothing to do with it.

*chuckle* No offense intended, and I'd be surprised if you were offended. Correct, I believe the fan is not the problem, nor is the CCRM. But I've ordered a used one from MPSauto just in case - they only want $45 each, compared to $400 new.

 

[Chythar]

This automatically means that the short is somewhere between the fuse and the CCRM. Retrace your wiring and see if it is pinched anywhere.

Well since I went through and hid wires on thic Cobra, it's entirely possible. I'll report back with my results.

 

[HISSIN50]

*chuckle* No offense intended, and I'd be surprised if you were offended. Correct, I believe the fan is not the problem, nor is the CCRM. But I've ordered a used one from MPSauto just in case - they only want $45 each, compared to $400 new.

Unless I missed something, I had no reason to be offended. I just try to help peeps, part of which is keeping unnecessary diagnostics to a minimum.

It's always nice to have a spare CCRM. Nice pick-up. If the part number on the one you get differs from yours, send me the number. I once put together a list with some cross-compatibility. I never post the list because I haven't physically verified some of the part numbers. As we know, some CCRMs plug right in but they have a few pins moved around, thus they don't plug-and-play without repinning. I have confirmed a few of the numbers however.


And I actually do get offended without a lot of effort (that's a general statement not pertaining to this thread. I like everyone that's posted on this one ).
There are some people on the forum who I simply won't respond to anymore because of a lack of respect (I might disagree with people but I always try to explicitly state that there's mutual respect involved and that we share a difference of opinion or experience. Some others don't seem to feel the same way). I won't even bother to disagree with some of these people anymore, though they're logic is flawed or just wrong.

[/Tangent off]

Short finders are simple devices that give an audible cue that helps find the short. In this case, I dont think it will help much (they're nice when you have a short between the engine harness and the trunk. Who wants to physically trace a wire, inch by inch, through the interior of the car).

Good luck with the wire chasing.

 

[Chythar]

Unless I missed something, I had no reason to be offended. I just try to help peeps, part of which is keeping unnecessary diagnostics to a minimum.

Don't think you missed something, I just read your previous response as a bit defensive. It's all good, forget I brought it up. Your input is always appreciated, and very helpful.

 

[Chythar]

Well, I think I found the problem already. When I hid the wires, I extended the BK/O wire for the cooling fan, as well as the other three in that connector: BK/W (ground), R (PCM power) and BK (A/C Clutch Coil Ground) The electrical tape covering the BK/O and BK/W had rubbed off in the same area, and it's likely the two were touching. Here's what I did:

* My voltmeter read 0.02 ohms on the BK/O wire from the CCRM to the fuse box. This is normal from what I've read.

* I disconnected connector C109, it's a 4-wire connector that holds the 4 wires I mentioned above, and it's the next connector downstream from the CCRM connector. I put in a new 60A fuse, and it popped as soon as I hooked up the negative terminal - same as before. This meant the short was farther along.

* I disconnected all the connectors on that part of the harness (to get some slack), then started unraveling the wire loom back to where I spliced the 4 wires above. I saw the bare wiring, so I separated the four wires from each other. I put in a new fuse and hooked up the battery . The fuse did NOT pop.

* I hooked up as many of the connectors as I could again. I couldn't hook them up all at once, so I tested them individually. Still, the fuse did NOT pop.

* Out of curiosity, I tested my fog lights and horn. Neither one works. So they are likely a separate issue.

Anyone see any flaw in my testing? I presume it's safe to wrap more electrical tape around the bare wiring and patch it all up.

 

[toyman]

Well, I think I found the problem already. When I hid the wires, I extended the BK/O wire for the cooling fan, as well as the other three in that connector: BK/W (ground), R (PCM power) and BK (A/C Clutch Coil Ground) The electrical tape covering the BK/O and BK/W had rubbed off in the same area, and it's likely the two were touching. Here's what I did:

* My voltmeter read 0.02 ohms on the BK/O wire from the CCRM to the fuse box. This is normal from what I've read.

* I disconnected connector C109, it's a 4-wire connector that holds the 4 wires I mentioned above, and it's the next connector downstream from the CCRM connector. I put in a new 60A fuse, and it popped as soon as I hooked up the negative terminal - same as before. This meant the short was farther along.

* I disconnected all the connectors on that part of the harness (to get some slack), then started unraveling the wire loom back to where I spliced the 4 wires above. I saw the bare wiring, so I separated the four wires from each other. I put in a new fuse and hooked up the battery . The fuse did NOT pop.

* I hooked up as many of the connectors as I could again. I couldn't hook them up all at once, so I tested them individually. Still, the fuse did NOT pop.

* Out of curiosity, I tested my fog lights and horn. Neither one works. So they are likely a separate issue.

Anyone see any flaw in my testing? I presume it's safe to wrap more electrical tape around the bare wiring and patch it all up.

That sounds fine but not knowing the wire gauge and what you mean by bare wire (pinched, cut, crushed, poor splice) might determine if there is a better solution than just taping the bare section.

 

[Chythar]

That sounds fine but not knowing the wire gauge and what you mean by bare wire (pinched, cut, crushed, poor splice) might determine if there is a better solution than just taping the bare section.

Sorry, I knew I left out some info. I'm not sure of the wire gauge, it's thicker and stiffer than most of the wiring in this harness so I'm going to guess 14 or 16 gauge. The wiring is not pinched, cut or crushed. This is a spliced part of the wire, which I did myself to extend the wiring harness. The splice is good and strong and decently soldered together, but my soldering iron had trouble heating the wire and solder so the soldering job isn't my best. In any splice, you will have wire that has the insulation stripped off; in this case, the splice has solder melted into it. I had wrapped electrical tape over the splice, but a small bit of the electrical tape has worn away allowing a small sliver of the splice to stick through.

As the phrase goes, a picture is worth a thousand words. So here's two thousand. The first is a picture of the four thicker wires up top, and some of the rest of the wiring harness below. These both happen to be the parts I extended, as you can see by the black electrical tape wrapped around each wire.

This second is a close-up of the BK/O wire. My camera won't focus that close up, but you can see the blurry copper bit in the center of the electrical tape. There's a smaller bare spot in the BK/W wire which matches up with the one in the BK/O wire.

 

[toyman]

Taping should be fine. Next time though I'd use water tight shrink wrap to cover the splice.

 

[BlownFiveLiter]

If there's an area where you can pop the wire out of the connector, it might not be a bad idea to run some heat shrink tubing down the wire and cover the spot. Maybe even two layers of it, just for some extra security.

 

[Chythar]

If there's an area where you can pop the wire out of the connector, it might not be a bad idea to run some heat shrink tubing down the wire and cover the spot. Maybe even two layers of it, just for some extra security.

Did two layers of heat shrink tubing AND some brush-on "liquid tape" for added measure. Looks nice and sturdy.

Just figured out the fog light and horn problem. Ran the tests in the bid Ford repair manual I have, and the trigger voltage wasn't coming in. Pulled the driver's splash guard to get to the next connector in line, and it wasn't plugged in all the way. Well, DUH. Plugged it in until it clicked, and I have fog lights and my horn back. Sweet!

Now to put everything back together.

 

[toyman]

Did two layers of heat shrink tubing AND some brush-on "liquid tape" for added measure. Looks nice and sturdy.

Just figured out the fog light and horn problem. Ran the tests in the bid Ford repair manual I have, and the trigger voltage wasn't coming in. Pulled the driver's splash guard to get to the next connector in line, and it wasn't plugged in all the way. Well, DUH. Plugged it in until it clicked, and I have fog lights and my horn back. Sweet!

Now to put everything back together.

That's great. As is so often the case it's the little things that get missed