update-not solved Or IS IT?! You Decide. See post 60

[sperold]

All I can say is follow the great logic put forward by ScotSHO. Get another SHO and do the same fuse sequence that you have done on your car. But start at 10, just like you did.
I wouldn't go beyond 30 unless you get some sound advice from someone who knows.

 

[sperold]

Hey, check post #34!
I sure hope that is it.

 

[93rev2sev]

alt tested fine, waiting to hear if a 150A fuse is appropriate.

 

[sperold]

There goes my thirty minutes of fame.
Best of luck on this, it has me worried and I am not even involved!

 

[ScotSHO]

alt tested fine, waiting to hear if a 150A fuse is appropriate.

Is this the wire going to the CCRM and PCM? I think Paul was talking about a different wire, but I'm not sure. 150 amps is huge, but possible. It should be called out on a wiring diagram. What size is the wire feeding that circuit, 6 gauge?

 

[ScotSHO]

Here is a 12V wire gauge chart, 150 amp using 6 gauge wire fits the chart. I would fuse the usage side of the CCRM for the fuel pump, cooling fan and the A/C coil with maybe 10 amp fuses each to start. Those 150 amp fuses aren't cheap.

http://www.offroaders.com/tech/12-volt-wire-gauge-amps.htm

 

[93rev2sev]

The wire at the battery is about 6 or 8 guage, I'd guess. It then necks down to the fusable link which looked like about 14-18 guage. After the link it branches into 2 separate yellow power wires of about 6-8 guage each. I'm thinking that they used a fusable link there (instead of a fuse) so that it could accept momentary amperage spikes in excess of it's rating without blowing (fan motor starting, A/C compressor clamping, etc..).

I'm going to get another fusable link from the yard and solder it in there.

 

[93rev2sev]

I went to the junk yard and picked up a couple of 20GA fusable links (the same as was there before).

After a little soldering, I plugged it in and it smoked.

Now I'm thinking that my problem is the ignition switch as that's literally the ONLY thing that moved since I was able to get the car started using a 30 amp fuse between the battery and those 2 yellow wires (CCRM and ECU power).

Thoughts?

 

[sperold]

I give up.
Put a seperate fuse box under the hood for those suspecious components CCRM, CPU, fuel pump and whatever else that harness does.
Change the switch if you want, but it sounds like a longshot. The 86 Taurus (I had one) had wiring harness problems in the steering column, where the big connectors plug together, but I thought that was ironed out by the time these things came around.
Did you smoke your new component?

 

[93rev2sev]

No, I don't think I blew the new CCRM. The fusable link smoked so fast...

I have everything disconnected but the battery and the computer (fuel pump, fan, alternator, A/C - all disconnected). The key is out of the ignition, yet there is still power to the car side of both of those yellow wires.

 

[sperold]

That doesn't sound right, unless that computer requires continuous power to keep its memory alive. Otherwise it has to boot up like your computer at home, which gets in the way of a fast get-a-way.

 

[needaQuaife]

make sure the battery posts are NOT touching hood when closed. Also make sure small lead on -negative battery post is intact. Follow both cables from battery to starter, they have insulation, not exposed and shorting out? I just had a fire due to short circuit, then upon replacing battery, another smoke and stall. New battery was too tall... second time ground from intake to firewall started melting & small lead off - post burned off into two seperate pieces.

 

[ScotSHO]

No, I don't think I blew the new CCRM. The fusable link smoked so fast...

I have everything disconnected but the battery and the computer (fuel pump, fan, alternator, A/C - all disconnected). The key is out of the ignition, yet there is still power to the car side of both of those yellow wires.

It could be the ignition, shoot, it could be lots of components. Do you have EVTM or wiring diagrams for this car? We need to find out where the power is going and what else can be shorted out. With the fusable link disconnected, do the yellow wires show a short (low resistance) to chassis ground?

It's almost time to start running temp power (with fuses) to things to see if a certain areas of the harness are bad.

With a schematic, we can think through the possibilities. I'd hate to smoke more CCRMs or a PCM. Think of it this way, if this was house wiring shorting out, it would have already caused a fire. (Proceed with caution)

 

[deercrusher]

when i said I have a spare harness laying around I wasn't bragging - let me know if you end up needing it - it'll be here for you.

 

[sperold]

I need an update on this thread.
I am dreading the day I have such a problem; and it would be comforting to know this one got solved.
A lot of those great looking SHOs in the wrecking yards, had a phase like this, that preceded their arrival.

 

[SHOtime2511]

any updates?

 

[shoon]

Throwing some things out there... I'm tired and this thread confuses me right now; so please bear with me not trying to be ignorant.

-Does it go into test mode (fan running blinking CEL) when you use the "paperclip" method since replacing PCM / CCRM?

-Did you remove / inspect the fuel pump electrical connector where it goes into the sending unit? Nothing melted?

-Do you have fuel injector pulse and / or spark? If not, does pulling the SPOUT change anything?

-Check and clean ALL chassis grounds in the engine bay. not sure about the 91's but I know my 95 has them on both sides of the inner fenders.


OR is it that the only issue your having right now, is that your frying CCRM's because of FP / wiring issues?

If the main issue you have is above^ I would suggest running new wire to the sending unit from the CCRM and repeating the test to see if you still pop fuses.. I am banking on a harness issue.

Because there WAS a short or high current draw of sorts, it could have very well melted some wiring causing another short.. or some wire insualtion could have rubbed through somewhere and its shorting out.

 

[93rev2sev]

Thanks,

I'll be putting my "wire harness hat" on this weekend.

 

[93rev2sev]

Started with the ignition switch...the harness connector looks charred and the switch itself is bowed in the middle. The switch didn't look burnt inside, but this charred connector worries me.

 

[TopGunnYFZ]

Yeah I would not run that either