97 Taurus Wagon blows EEC fuse when at operating Temp

[jobrien]

My 97 Taurus blows the EEC fuse when it reaches operating Temp. I have change the CCRM, I have disconnected both cooling fans and temp sensors while engine is still hot and fuse still blows, the fuse blows both with the A/C on and off. When the engine cools I can replace the fuse and the car will start. Im at a loss. Anyone have any suggestions.

[shorod]

Do you have the specific fuse location number/circuit number? I can check the schematic to see what else is on that circuit. Also, is this the instrument panel fuse panel (in the passenger compartment) or the engine compartment fuse panel (under the hood).

Have you attempted to pull diagnostic codes from the PCM to see if it recognizes any issues? You may have a component internal to the PCM that goes low in resistance when warm, or an electrolytic filter capacitor that is faulty inside the PCM.

-Rod

[jobrien]

I have an OBD II code reader and there are no codes and the check engine light is not on when the engine is running. The fuse is labled as the "EEC" in the power distribution box under the hood. From what I have read so far I believe the power from this fuse goes to the CCRM which contains the EEC power relay, the fuel pump relay, the low and high speed fan control relays, A/C relay, B+ to the PCM, B+ the the inertia fuel shut off, B+ to A/C compressor clutch, Wide-open throttle signal to PCM and A/C clutch signal to the PCM.

[shorod]

Is it a 30A fuse located in position 2 of the engine compartment fuse/relay box? My service manual only lists the fuses by location number, not by name. The underside of the fuse box cover will probably have a location number shown for the fuse location.

I'm looking in my service manual for the 1998 model year and it appears the relays are discrete relays in the engine compartment fuse/relay box rather than the CCRM. In 1998, fuse 2 controlled power for most of the same relays that were part of the CCRM in the past. If this is the case on your 1997 as well, you should be able to pull the relays one at a time to narrow down which circuit causes the fuse to blow. Of course you don't want to prevent the cooling fans from working when the car is at operating temp....

For some reason, the wiring diagrams on my 1997 service manual DVD are corrupt, so I cannot get details on 1997.

-Rod

[jobrien]

It is a 30 amp fuse and I believe it is #2 on the schematic. It is located in the top left location in the power distribution box under the hood. According to the haynes manual I am reading the EEC power relay is part of the CCRM on 96 and 97 mdls. On 98 and later models the relay is in the distribution box. I have a chart that shows what each pin is for on the CCRM. I have disconnected the fans while the engine is hot and blowing the fuse and tried to replace the fuse with the fans and both temp sending units disconnected and it still blows the fuse until everything cools down. One ford mech told me the alt was putting out to much voltage "14.26". But I disconnected the Alt and the fuse blew when operating temp was reached and the battery was at 10.28 volts at the time the fuse blew so that eliminated that.

[shorod]

Once the fuse blows, will it blow as soon as it's replaced, or only if the key is in the RUN position? How long does the engine have to cool before you can replace the fuse without it blowing?

If you have a few minutes of cooling time, you could unplug the CCRM completely and replace the fuse. If the fuse blows, then you know you need to look elsewhere. If the fuse does not blow, you can use the test light on the various supply wires to the CCRM and see which one causes the test light to glow VERY brightly. That wire (or wires) is the main culprit. Don't stop at the first bright wire you find though, continue to check others.

I'd suggest you try unplugging the fuel pump inertia switch first and see if that keeps the fuse from blowing. Maybe you have a fuel pump that is going low in resistance (shorting) after it's been operating for a long period of operation.

-Rod