Hello, 19 year old from Indiana here, got a small electrical problem with my black 97 Cobra 4.6 4 valve, when I bought the car, the wiring was completely fubar. Not exactly sure what the previous owner has all done or changed on the car but nevertheless I have a positive wire cable hanging down beneath the oil pan, for some time it was held against the pan by another part of the harness that sits down there, recently i believe it’s been grounding out on the pan and causing the car to randomly have electrical problems on the road, check engine light starts flashing, as do all the other warning lights and the car starts to have a mind of its own. It randomly will rev and do weird things like jerk and buck while in gear however I try to stop and turn the car off when this happens if it doesn’t already shut off by itself. (I’ve lost all power and had to use manual steering and manual brakes trying to turn off of a 50 mph road) I’m not exactly sure this is 100% the problem but I’d love to know where this dangling cable routes to and any other helpful info from you sn95 veterans. Thanks in advance!
Could use some help with wiring routing
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wmburns
SN Certified Technician
wmburns
SN Certified Technician
The wire in question is the motor grounding strap. It goes from the left hand motor mount to the car's frame rail.
It is frequently over looked during a motor swap and simply ripped out.
It is frequently over looked during a motor swap and simply ripped out.
Don’t mean to overstep my boundaries but isn’t that a hot wire? So how could it be the ground strap if it’s a hot wire, I would think that means it should be hooked up to something as a positive end not as a ground
wmburns
SN Certified Technician
Weeeeellllll................ Why don't you tell me what the other side of that strap is attached to? Perhaps the frame rail? Or the motor mounts????
Orrrrr is there another grounding strap on the left hand motor mount?
But since you have doubts, why not perform some tests for yourself so that you can feel good about it? Using a Volt-Ohm meter (VOM) measure the voltage difference between the wire and battery negative? Could it be zero (or very near zero)? IF it's a power wire as you believe then there should be some voltage at the wire?
Howto perform charging system voltage drop test
Howto perform charging system voltage drop test
To anyone else reading any of my posts I usually include the line: Today's cars simply will not run right without a strong battery and charging system! Cut corners here at your own risk I'm a big believer in starting with the basics. As such I...
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Want more tests? Perform a voltage drop test between the alternator case and battery negative. Does the amount of voltage DROP when the ground strap is connected?
Bottom line. There is supposed to be a motor grounding strap that goes from the left hand motor mount stud to the car's frame rail. Some model years a bare braided flat wire. Some have a red rubberized coating. Looks a ton like your picture.
OBTW, I suspect that the electrical problems you are having are because the ground wire ISN"T connected. EXPECT problems when heavy loads switch on such as the radiator cooling fan if this motor grounding strap is missing. I have help more than one person that have problems with the motor apparently over heating when the cooling fan kicks on. In many cases the problem was traced to voltage dropping as load increased. The cause being a poor motor ground not allowing the alternator to return enough current.
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I’m having the same issue, had a new 4 valve motor from an 01 cobra put in and the guy probably didn’t use thread locker on any of the bolts, a few weeks ago I had my ground strap come off and I was dropping voltage while on the road. So not exactly safe.. but my question is, where is the best location to hook up this ground strap on the motor? It’s very tight on the drivers side chassis, but don’t exactly know where to hook her back up to. Any suggestions?Weeeeeeell................ Why don't you tell me what the other side of that strap is attached to? Perhaps the frame rail?????
Orrrrr is there another grounding strap on the left hand motor mount?
But since you have doubts, why not perform some tests for yourself so that you can feel good about it? Using a Volt-Ohm meter (VOM) measure the voltage difference between the wire and battery negative? Could it be zero (or very near zero)? IF it's a power wire as you believe then there should be some voltage at the wire?
Howto perform charging system voltage drop test
Howto perform charging system voltage drop test
To anyone else reading any of my posts I usually include the line: Today's cars simply will not run right without a strong battery and charging system! Cut corners here at your own risk I'm a big believer in starting with the basics. As such I...
Want more tests? Perform a voltage drop test between the alternator case and battery negative. Does the amount of voltage DROP when the ground strap is connected?
Bottom line. There is supposed to be a motor grounding strap that goes from the left hand motor mount stud to the car's frame rail. Some model years a bare braided flat wire. Some have a red rubberized coating. Looks a ton like your picture.
OBTW, I suspect that the electrical problems you are having are because the ground wire ISN"T connected. EXPECT problems when heavy loads switch on such as the radiator cooling fan if this motor grounding strap is missing. I have help more than one person that have problems with the motor apparently over heating when the cooling fan kicks on. In many cases the problem was traced to voltage dropping as load increased. The cause being a poor motor ground not allowing the alternator to return enough current.
wmburns
SN Certified Technician
On the motor mount is a two sided stud. One side of the grounding strap goes there.
The other end attaches to a the bottom of the frame rail at a point straight across from the motor mount.
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