Various electrical issues I can't figure out

[KidWithAGT]

For a little over a week now I've had a slowly growing list of what I'm pretty sure are electrical/wiring issues. Once I know what to do I shouldn't have any real trouble fixing it, but for the life of me I can not diagnose this stuff.
My issues right now are:
- Cooling fan always runs when the key is on, whether or not the engine is. It does not run with the key off.
- Airbag code 24 (If I'm reading the airbag code right)
- Battery light on while engine is running
The battery light is the newest and most immediately concerning issue, no clue what's causing it. With the engine off the battery voltage maintains about 12.4, and with the engine on it's 14.2. Other than low battery or incorrect charging voltages, what could cause the light to turn on? And what should I do to attempt to diagnose the other issues?

 

[ttocs]

what year? Start simple and check your grounds. By check I mean remove, clean and then tighten back down enough that they do not move/wiggle at all.

 

[KidWithAGT]

95 GT, been checking and cleaning them as I find them. Only ones I've found so far though are the two next the the battery, one in a similar spot on the passenger side and the one next to the ECU. Any others?

 

[ttocs]

I think the block to chassis ground is by the oil filter/sender if I remember the stock location correctly but it has been so long since my wiring was stock I could be wrong.

 

[KidWithAGT]

Well, cleaning the main block ground was quite the annoying task, the stud mounting it to the block was absolutely messed up. But, that's done finally. I also heard there is supposed to be a ground between the back of the engine and the firewall, any idea where exactly that is/was on the firewall? And if it's not there, where else can I attach a new ground to the firewall?

Edit: it's also probably worth adding that cleaning that ground hasn't fixed the issues. Something else interesting however is that when I finally reconnected the battery and went to test it, the fan didn't turn on immediately. It seemed like the airbag code had gone away while the battery was disconnected, but presumably came back when the diagnostic module reran its tests. It seems like the fan only kicked back on when the airbag diagnostic module had decided there was a problem a couple seconds after turning the key to run. Not sure if that was actually the case or if the two events were unrelated. It does make me wonder if fixing the airbag issue might magically fix the fan though. Not sure what to think about the battery light.

 

[KidWithAGT]

Anyone have a picture of where that hole in the firewall is? I heard it's below the throttle cable, but I can't find it anywhere

 

[ttocs]

Anyone have a picture of where that hole in the firewall is? I heard it's below the throttle cable, but I can't find it anywhere

not sure what hole you mean.

I can't remember a ground on the back of the motor myself but again mine has not been stock for so long that if someone else remembers, ignore me. If you want to add a ground a good/easy place to do it(as long as your not running long tubes) is to use one of the bolts that holds the starter to the block for the block ground and make a nice clean spot on the chassis next to it. The starter pulls more current than anything on the motor.

 

[KidWithAGT]

Well I'll see what I can do about adding an extra ground in then, can't hurt and I've already got the strap. Assuming it's not dirty/loose grounds causing my issues, what should I be checking next?

 

[cobrajeff96]

As for key on/fan on, might just be a bad temp sensor (that'll be the two-pin sensor for the ECU, not the single lead sensor for the gauge cluster).

As for battery light with nominal voltages and battery maintaining a good charge as you mentioned, it could just be a blow 400 Ohm resistor on the back side of the cluster or possible a burnt or misaligned tracer wire on the back of the cluster right where the connectors snap in. Could be other things possibly, but those things do come to mind.

 

[KidWithAGT]

As for key on/fan on, might just be a bad temp sensor (that'll be the two-pin sensor for the ECU, not the single lead sensor for the gauge cluster).

As for battery light with nominal voltages and battery maintaining a good charge as you mentioned, it could just be a blow 400 Ohm resistor on the back side of the cluster or possible a burnt or misaligned tracer wire on the back of the cluster right where the connectors snap in. Could be other things possibly, but those things do come to mind.

Ah, I hadn't considered that something around the light might've gone bad. I'll have to get in there and check that. as far as the temp sensor goes though I'm pretty certain it's not broken. I've checked from both the pins at the back of the sensor as well as the pin on the ECU's connector and it always showed the correct resistance for the engine's temperature.

 

[cobrajeff96]

Did you back-probe the sensor pins while key was on? That's about the only way to properly measure it.

 

[KidWithAGT]

I don't see how that would make any difference. A current passes through the sensor based on its resistance, and that resistance changes based on the sensors temperature. So by measuring the sensors resistance and checking if it matches with what it should be for the given temperature, that should show it is working whether or not the key is on, right? There should be no reason the resistance suddenly changes when the key is on.
Btw this is all based on my somewhat limited knowledge of electronics and such, please correct me if I'm wrong.

 

[cobrajeff96]

Eh maybe, if the values are pretty spot on then maybe you got an accurate measurement. Better yet, if you're able to run a scan tool on the OBD-II port and read the temp that's a sure way to verify it's working. If so, then maybe suspect the CCRM module. Also while you're at it make sure the fan power wires aren't cooked right at the fan connector.

 

[KidWithAGT]

I don't believe it's the ccrm, if either of the relays in there were stuck it'd likely cause the fan to run at all times even with the key off. I'm beginning to think this is a strange symptom of an issue outside the fan circuit given the strange combination of issues and lights I've got.

 

[07GtS197]

I didn’t read everything but did you check for 5v reference voltage at the temp sensor?

 

[dalpoas83]

For a little over a week now I've had a slowly growing list of what I'm pretty sure are electrical/wiring issues. Once I know what to do I shouldn't have any real trouble fixing it, but for the life of me I can not diagnose this stuff.
My issues right now are:
- Cooling fan always runs when the key is on, whether or not the engine is. It does not run with the key off.
- Airbag code 24 (If I'm reading the airbag code right)
- Battery light on while engine is running
The battery light is the newest and most immediately concerning issue, no clue what's causing it. With the engine off the battery voltage maintains about 12.4, and with the engine on its 14.2. Other than low battery or incorrect charging voltages, what could cause the light to turn on? And what should I do to attempt to diagnose the other issues?

MS3 94/95 Fan Control

I just built a DIY MS3 / 3.0 kit, and I built my own harness connector from a Ford Rotunda system. It actually started the car first try today, surprisingly. I didn't connect up any fan wiring yet, so I couldn't start tuning my car. I think the best idea is to use the PWM IAC outputs to...

www.corral.net

 

[dalpoas83]

 

[KidWithAGT]

View attachment 26502

Interesting, that's good to know. So it might not necessarily be that something is telling the fan to turn on, but rather failing to tell it to turn off.

 

[KidWithAGT]

I didn’t read everything but did you check for 5v reference voltage at the temp sensor?

Finally got around to checking, got about 4.6-4.7 volts with key on engine off. Is that close enough or does that indicate some upstream issue?
Also replaced the temp sensor just to be sure, no change.

 

[dalpoas83]

Finally got around to checking, got about 4.6-4.7 volts with key on engine off. Is that close enough or does that indicate some upstream issue?
Also replaced the temp sensor just to be sure, no change.

That’s close enough