Hello everyone I am in desperate need for some advice for my 1989 coupe. I’m having an electrical problem. So before the fire my #8 fuse kept popping and now even with ya changing the entire dash harness my number 8 fuse is popping still and causing the car to lope And this is even after installing a completely different fuse box since it was the he entire harness complete Any ideas ?
Foxbody Electrical Fire Please Help
- Thread starter Laila Dee
- Start date
Fuse 8 should be for the courtesy lamps, glove box lamps, vanity lamps, cargo, engine compartment light, ect. Sounds like you have a short in the wiring somewhere going to one or more of these accessories. Since these accessories are all throughout the vehicle, unless you replaced the entire vehicle's electrical harness and switches you might not have found/replaced the issue.
Here is a wiring diagram for an 87-93 mustang. You are looking for all the accessories toward the middle/bottom that have the "LT GRN - YEL" wiring connected to them. You can see toward the bottom right where it says "Glove Box LT" that the "LT GRN - YEL" wiring is connected to fuse #8.
To troubleshoot, you will need to test all this wiring coming from fuse #8 at each connection point to figure out where it is shorted to ground. You can also disconnect each accessory that is connected to fuse #8, put a good fuse back in and see if the fuse blows. If it does, you know its in the wiring. If it doesn't, then there is something wrong at one of the accessories, then you can test each accessory one by one. I usually use a test light to test the circuit each time I plug something in so I don't have to keep going back to check the fuse. It could be a pinched/shorted wire, a bad switch, or something else.
You can also check the gray/yellow wiring coming from the ignition switch to fuse #8 for any shorts/bare wire as this would blow the fuse.
I've heard of a couple people that have had this issue and it was the wiring going to the map lights/vanity lights. Usually the wiring to the map light breaks where it bends and shorts out. Might be one of the first areas you want to check.
Here is a wiring diagram for an 87-93 mustang. You are looking for all the accessories toward the middle/bottom that have the "LT GRN - YEL" wiring connected to them. You can see toward the bottom right where it says "Glove Box LT" that the "LT GRN - YEL" wiring is connected to fuse #8.
To troubleshoot, you will need to test all this wiring coming from fuse #8 at each connection point to figure out where it is shorted to ground. You can also disconnect each accessory that is connected to fuse #8, put a good fuse back in and see if the fuse blows. If it does, you know its in the wiring. If it doesn't, then there is something wrong at one of the accessories, then you can test each accessory one by one. I usually use a test light to test the circuit each time I plug something in so I don't have to keep going back to check the fuse. It could be a pinched/shorted wire, a bad switch, or something else.
You can also check the gray/yellow wiring coming from the ignition switch to fuse #8 for any shorts/bare wire as this would blow the fuse.
I've heard of a couple people that have had this issue and it was the wiring going to the map lights/vanity lights. Usually the wiring to the map light breaks where it bends and shorts out. Might be one of the first areas you want to check.
What kind of damage do you have from the fire? If the car itself is in good shape, I would be more willing to replace the entire body harness than start with another car. These cars are old, and there is no telling what you may end up with in the next one.
@Laila Dee
I have an 89 5.0 LX which is almost identical to the GT.
I also have the 89 Mustang EVTM which is the troubleshooting manual for electrical and vacuum systems. I can copy whatever pages you need once you have narrowed down what needs further inspection and troubleshooting.
PM me your email address and I will send you a complete Ford Factory 89 Mustang electrical diagram set. The zip file is 2.5 MB and is too big to fit through Stangnet's email gateway.
The plug shapes on the diagrams match the plug shapes on the actual plug. The diagram is divided up by the layout of the car. The first diagram is for the very front of the car, and it works its way to the rear of the car page by page.
They are in a zip file format to reduce the size of the package. If you don't have Windows 7 or Windows 8, or later, you’ll need WinZip or other Windows archive tool to extract them from the zip file.. See www.majorgeeks.com - Download Freeware and Shareware Computer Utilities for a free download.
You will need the Adobe Acrobat viewer which is also a free download – www.adobe.com/products/acrobat/readstep2.html - Adobe Reader download - All versions
I have an 89 5.0 LX which is almost identical to the GT.
I also have the 89 Mustang EVTM which is the troubleshooting manual for electrical and vacuum systems. I can copy whatever pages you need once you have narrowed down what needs further inspection and troubleshooting.
PM me your email address and I will send you a complete Ford Factory 89 Mustang electrical diagram set. The zip file is 2.5 MB and is too big to fit through Stangnet's email gateway.
The plug shapes on the diagrams match the plug shapes on the actual plug. The diagram is divided up by the layout of the car. The first diagram is for the very front of the car, and it works its way to the rear of the car page by page.
They are in a zip file format to reduce the size of the package. If you don't have Windows 7 or Windows 8, or later, you’ll need WinZip or other Windows archive tool to extract them from the zip file.. See www.majorgeeks.com - Download Freeware and Shareware Computer Utilities for a free download.
You will need the Adobe Acrobat viewer which is also a free download – www.adobe.com/products/acrobat/readstep2.html - Adobe Reader download - All versions
Last edited:
Blown88GT
Founding Member
Looks like you have an '89 GT.
How bad was the fire? Got any pics? Where are you located? Could the cause of the fire be due to the installation of the new dash harness?
Similar threads
- Poll
