97 cobra electrical problems

olcobra97 · Feb 8, 2022

Hi all I have a 97 cobra I'm noticing a couple of electrical hiccups here and there. For example, the coolant low light comes on for a split second and goes off. It almost always comes on on a cold start. The coolant looks fine and topped up. The tachometer is finicky, it tends to work at higher speeds but at idle it shuts off. Both the tachometer and speedometer take a little while to get moving from a cold start. As I understand Fords with the C-NORMAL-H gauges it's okay for it to read anywhere in the Normal range but I was a little concerned today seeing it go over the halfway mark after a 20 minute drive just backing into the garage. I have also heard these are not super reliable either way, any words of advice?

COramprat · Feb 8, 2022

Have you had to add coolent recently? The two issues may be related. The system needs to be "burped" in order for it to work properly.

olcobra97 · Feb 8, 2022

COramprat said:
Have you had to add coolent recently? The two issues may be related. The system needs to be "burped" in order for it to work properly.

I have not. I've only had the car since this Saturday. I have kept an eye on the coolant level and it's been fine so far. I'm led to believe something is shorting or damaged on the board the tach is attached to. Either way, I'm putting it up in the air tomorrow to see if it's leaking from anywhere. I've heard that a common point to look out for is the coolant crossover tube, mine is rusty but it doesn't seem to leak. I will probably bleed the system soon, but I need to learn the process for that

COramprat · Feb 8, 2022

I'm leaning to properly burping the system. There is a plug in the coolent crossover that you remove and fill from there. Run the car and let it come to operating temp. Make sure coolent is flowing through the tube. You may have to do that a few times to ensure it's full.

As far as the tach and speedo I'm no help there. Sounds like a signal problem with the tach.

olcobra97 · Feb 8, 2022

COramprat said:
I'm leaning to properly burping the system. There is a plug in the coolent crossover that you remove and fill from there. Run the car and let it come to operating temp. Make sure coolent is flowing through the tube. You may have to do that a few times to ensure it's full.

As far as the tach and speedo I'm no help there. Sounds like a signal problem with the tach.

Okay. I'll keep that in mind. The car made it about an hour, hour and a half home on the highway with no issues besides the coolant light coming on every once in a while. I need to take it for inspection anyway tomorrow, so I'll see if it's leaking or anything and report back with that. The only other issue I have electrically is what I think is a bad blinker stalk, it's able to completely cut the headlights off if you wiggle it around while on high-beams and sometimes won't hold itself down/up for blinkers.

Not sure with the tach problem, when it reads it reads correct, same as the speedo. The odometer works just fine all the time too. There's a bunch more stuff I may need help getting done but none of it's electric. Thanks for the help!

olcobra97 · Feb 9, 2022

olcobra97 said:
Okay. I'll keep that in mind. The car made it about an hour, hour and a half home on the highway with no issues besides the coolant light coming on every once in a while. I need to take it for inspection anyway tomorrow, so I'll see if it's leaking or anything and report back with that. The only other issue I have electrically is what I think is a bad blinker stalk, it's able to completely cut the headlights off if you wiggle it around while on high-beams and sometimes won't hold itself down/up for blinkers.

Not sure with the tach problem, when it reads it reads correct, same as the speedo. The odometer works just fine all the time too. There's a bunch more stuff I may need help getting done but none of it's electric. Thanks for the help!

Self-reporting here:

When driving, the coolant light only tends to come on at a lower speed, and only for a few seconds. The temp gauge stayed between the O and R of "NORMAL" the whole way, only rising just under the middle under acceleration up a hill for a few moments or at idle after 30 minutes of driving. It did not go over half today.

As for leaks, it doesn't seem to be leaking coolant at all - maybe it's evaporating through that crossover but I can't smell or see it. It was leaking from the rack and pinion pretty bad which I'll put down to moving it after it had sat for about a year.

I think my steps would be to check the fuses and take the cluster out and check for a burnt trace or diode, etc.

Here's a picture of the temp gauge from yesterday, just a little over half.

Akumu No Dara Ra · Feb 9, 2022

To me it feels like you may simply have a slight grounding issue. The gauges on these are dummy gauges. By the time they read hot, it's too late.

A visual inspection turned up nothing, right? My money is that it's a grounding issue. Try checking for continuity in the wires going to the gauge cluster. Trace each one from terminal to terminal and see what they should be reading. If any read low, try to see where it's grounding. Electrical issues are never fun. Good luck. Do live in an area where there are bound to me mice?

COramprat · Feb 9, 2022

The temp gauge is fine. As long as it doesn't go hot you are good. I was thinking if the low coolant light comes on and the temp was running hot it would be a minor low coolant issue. The temp range that you see is pretty normal. I'm guessing the float may be sticking and causing the light to flash.

Akumu No Dara Ra · Feb 9, 2022

COramprat said:
The temp gauge is fine. As long as it doesn't go hot you are good. I was thinking if the low coolant light comes on and the temp was running hot it would be a minor low coolant issue. The temp range that you see is pretty normal. I'm guessing the float may be sticking and causing the light to flash.

^

Without actually looking at it in person it's hard to say. That's why dealerships and repair shops won't take a stab at it over the phone.

COramprat · Feb 9, 2022

Akumu No Dara Ra said:
^

Without actually looking at it in person it's hard to say. That's why dealerships and repair shops won't take a stab at it over the phone.

I'm going by experience. My son had a 98 Cobra that blew a top hose when he was working in Iowa. I had to diagnose what was going on from a thousand miles away. He wound up all good and coming home in the car a few months later.

Akumu No Dara Ra · Feb 10, 2022

COramprat said:
I'm going by experience. My son had a 98 Cobra that blew a top hose when he was working in Iowa. I had to diagnose what was going on from a thousand miles away. He wound up all good and coming home in the car a few months later.

In my experience, a coolant hose is a lot more obvious than an electrical issue. First and foremost, you can actually see a hose that's come loose or ruptured 100% of the time by tracing the leak. An electrical issue is not so apparent. I also don't have more than 20 years of experience working on cars, maybe 10 in any real capacity, so someone who has extensive experience may be better, especially someone who knows the platform like the back of their hand.

Your assessment is also very viable, not saying it's wrong or off in any way. It was more "agreed, *additional, unrelated info*"

COramprat · Feb 10, 2022

Akumu No Dara Ra said:
In my experience, a coolant hose is a lot more obvious than an electrical issue. First and foremost, you can actually see a hose that's come loose or ruptured 100% of the time by tracing the leak. An electrical issue is not so apparent. I also don't have more than 20 years of experience working on cars, maybe 10 in any real capacity, so someone who has extensive experience may be better, especially someone who knows the platform like the back of their hand.

Your assessment is also very viable, not saying it's wrong or off in any way. It was more "agreed, *additional, unrelated info*"

I wasn't really referring to the electrical issue. The coolent level and his impression that the temp was an issue as felt was related and separate from the tach and speedo issue. I separated that in my response.

Akumu No Dara Ra · Feb 10, 2022

COramprat said:
I wasn't really referring to the electrical issue. The coolent level and his impression that the temp was an issue as felt was related and separate from the tach and speedo issue. I separated that in my response.

Ugh. I totally misread. My bad. I need to stop posting with pre-caffeine brain.

olcobra97 · Feb 10, 2022

Akumu No Dara Ra said:
To me it feels like you may simply have a slight grounding issue. The gauges on these are dummy gauges. By the time they read hot, it's too late.

A visual inspection turned up nothing, right? My money is that it's a grounding issue. Try checking for continuity in the wires going to the gauge cluster. Trace each one from terminal to terminal and see what they should be reading. If any read low, try to see where it's grounding. Electrical issues are never fun. Good luck. Do live in an area where there are bound to me mice?

Me too. I'm going to go ahead and do that and check fuses anyway. I'll probably replace the float and burp the coolant as well. There's no mice around here, I'll have to learn the electrical part of this, I've got a multi-meter, anything else I'll need?

Thanks much

Akumu No Dara Ra · Feb 10, 2022

olcobra97 said:
Me too. I'm going to go ahead and do that and check fuses anyway. I'll probably replace the float and burp the coolant as well. There's no mice around here, I'll have to learn the electrical part of this, I've got a multi-meter, anything else I'll need?

Thanks much

Probably some metal pins to stick into the wires at various points, electrical tape, and if you do find an issue, some sort of connector, but what kind will depend on the wire that's bad, assuming there is one.

olcobra97 · Feb 10, 2022

Akumu No Dara Ra said:
Probably some metal pins to stick into the wires at various points, electrical tape, and if you do find an issue, some sort of connector, but what kind will depend on the wire that's bad, assuming there is one.

Thanks again - what're the metal pins for? Providing ground?

Akumu No Dara Ra · Feb 10, 2022

olcobra97 said:
Thanks again - what're the metal pins for? Providing ground?

They're so you don't have to pull the wires apart if you don't have continuity. You'll probably not need them unless you're arcing/grounding somewhere. Probe every foot or so along the wire using one pin, and check each time you move the pin along. You only have to do that if there's no continuity going from one end to another. This will help you determine the rough area of where the wire is grounding, assuming it is an grounding issue and not a faulty part.

Look at the backside of the gauge cluster itself. I conferred with my wife- she said check for a cold solder issue, do a visual inspection for anything that seems burned, cracked, etc. If it's only when cold then it's probably not arcing like I think it is but it's just not going to the right place. This is probably the easiest place to start.

7991LXnSHO · Feb 10, 2022

Pins are also helpful for probing the connectors from the backs without taking anything apart.
Edit, I have various sized safety pins in my kit for this.

olcobra97 · Feb 10, 2022

Akumu No Dara Ra said:
They're so you don't have to pull the wires apart if you don't have continuity. You'll probably not need them unless you're arcing/grounding somewhere. Probe every foot or so along the wire using one pin, and check each time you move the pin along. You only have to do that if there's no continuity going from one end to another. This will help you determine the rough area of where the wire is grounding, assuming it is an grounding issue and not a faulty part.

Look at the backside of the gauge cluster itself. I conferred with my wife- she said check for a cold solder issue, do a visual inspection for anything that seems burned, cracked, etc. If it's only when cold then it's probably not arcing like I think it is but it's just not going to the right place. This is probably the easiest place to start.

Appreciated. I will check that tomorrow and get back to you.

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