Electrical 1990 GT - Weird Electrical Issue

90foxbody00

New Member
Dec 22, 2018
21
1
3
20
Washington
Ok so for about a week now I've been getting this odd electrical issue with my 90 GT only when it's raining (I live in Seattle so pretty much everyday that ends with Y). It started last Friday when I was heading home from work, the radio will cut out for about half a second and the wipers will stop for between 30 seconds to a minute and a half, and it will sometimes cause the car to shudder when the radio cuts out. I checked and cleaned the main ground and the 2 grounds on the driver's side fender apron and that didn't really do anything. It seems like a connector issue but I'm not sure exactly which one could be the culprit. Any help would be great
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
17,222
5,512
193
polk county florida
So is your solution going to be to not drive in the rain?
you have to start somewhere and I gave you a starting point. These cars are not modern sealed capsules, they are old and problematic when it comes to daily operations.
without hands on diagnostic ability I can only offer best guess answers.
 

90foxbody00

New Member
Dec 22, 2018
21
1
3
20
Washington
So is your solution going to be to not drive in the rain?
you have to start somewhere and I gave you a starting point. These cars are not modern sealed capsules, they are old and problematic when it comes to daily operations.
without hands on diagnostic ability I can only offer best guess answers.
Yeah that wasn't going to be my solution as I said that was the reason my initial guess was an issue with one of the connectors.
 

jrichker

StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
27,245
2,594
234
74
Dublin GA
lowendmac.com
Yeah that wasn't going to be my solution as I said that was the reason my initial guess was an issue with one of the connectors.
Recall on Ford Ignition switches:

Revised 7-June-2014 to add Torx bit picture and source. Also added replacement ignition switch wiring pigtail picture, part numbers and sources.

Some of the symptoms of ignition switch problems are things that don’t work or are intermittent like radio, turn signals, wipers or heater.

There was a FREE recall on Ford ignition switches. They overheat and sometimes catch fire. That burns up the steering column and sometimes the car interior. Since this is very old information, you may not be able to get the switch replaced for free anymore. The auto parts stores sell the switches for $13-$15.







While you are working on the switch, check the wiring and connector closely. A replacement connector with new wiring pigtails is available from most auto parts stores

AutoZone and Advanced Auto Parts have the same Part Number: 434 - may have to order, not always in stock

Advanced Auto Parts alternate part number: PT5534



Saleen0679 was nice enough to dig this up for us awhile back: How to replace ignition switch on 1979-1993 Mustangs.
http://www.mustangandfords.com/how-to/engine/5657/


Torx bit set from Advance Auto Parts



Autocraft torx bit set – have small hole in tip for tamper proof screws.
Part No. AC571/W1386 Cost approx. $12 +tax

Diagrams courtesy of Tmoss & Stang&2birds

Ignition switch wiring
IgnitionSwitchWiring.gif


Fuel, alternator, A/C and ignition wiring
fuel-alt-links-ign-ac.gif


See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

O2 sensor wiring harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangO2Harness.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pin out
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif

Visual comparison of the Ford Fuel Injectors, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg
 

Waggellum

Member
Oct 5, 2019
6
3
13
51
Kennesaw, ga
First, i am not an expert by any means, but I would look at Jrichker's solution - when my mustang was new (3 months old) I had almost the same identical issue you described (my headlights also went out - interesting story with that, I wont go into it, but it near got me killed.
 

Blown88GT

Founding Member
Nov 13, 1999
2,110
494
134
Palm Beach Gardens, FL
First, i am not an expert by any means, but I would look at Jrichker's solution - when my mustang was new (3 months old) I had almost the same identical issue you described (my headlights also went out - interesting story with that, I wont go into it, but it near got me killed.
GT headlamps were a different issue, TSB 89-17-11, not a recall.
 
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