Electrical 1990 GT - Weird Electrical Issue

90foxbody00

New Member
Dec 22, 2018
21
1
3
19
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
 
  • Sponsors(?)


General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
16,418
5,237
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
19
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
27,357
2,824
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
50
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
1,977
449
124
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.
 
Thread starter Similar threads Forum Replies Date
F 1990 Weird battery issue Fox 5.0 Mustang Tech 8
T Cranks but wont start 2.3L (N/A & Turbo) Tech 4
B For Sale 1990 mustang parts for sale Fox Body Mustangs For Sale (1979-93) 1
C Just got a 1990 lx notchback. I need help please 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 10
J Fox 5.0 1990 T5 manual transmission issue. 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 8
P 1990 LX 5.0 auto trans shifting issue Fox 5.0 Mustang Tech 2
J 1990 saleen ACT and ECT sensor location Fox 5.0 Mustang Tech 4
91GTstroked WTB/Trade 1990-92 emerald green GT Fox Body Mustangs For Sale (1979-93) 1
9 What's it Worth? 1990 Restored Mustang 800hp What is it Worth?!?!? 3
G WTB/Trade 1990-1993 Notchback 5.0 budget under $14k Fox Body Mustangs For Sale (1979-93) 1
1 1990 mustang gt running like crap when hot,but good when first start up. Fox 5.0 Mustang Tech 18
C New Member 1990 Notch Project 66,000 Miles 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 7
J 1990 Mustang radio head unit install . Mustang Sound & Shine All 0
W 1990 mustang treated badly, needs restore engine upgrade 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 7
O 1990 7-up information needed 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 4
O 1990 7-Up The Welcome Wagon 0
3 1990 fox mustang no spark 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 3
J Fox My 1990 Notch 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 12
T 1990 GT Foxbody Door lock- help Fox 5.0 Mustang Tech 3
KaptKane Engine 1990 5.0 Engine "stutter" miss Fox 5.0 Mustang Tech 11
J Electrical 1990 Mustang GT Convertible Driver Side Window Not Working Fox 5.0 Mustang Tech 2
J Electrical 1990 Mustang GT Convertible Drivers Side Window Not Working? Fox 5.0 Mustang Tech 0
S Idle problem 1990 with gt40 crate engine 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 1
S Electrical What dash harness for a 1990 GT ? Fox 5.0 Mustang Tech 0
T Should I change the fluid in my 1990 AOD? 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 8
T Coolant in oil! 1990 5.0 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 6
S Engine 5.0 Running Rough (1990) Fox 5.0 Mustang Tech 1
Vaughnmx Engine 1990 fox car runs great unti it goes into closed loop runs vary rough popping backfire no power please help Fox 5.0 Mustang Tech 14
N 1990 5.0 engine and valve cover paints 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 0
S Engine 1990 Mustang GT Fox 5.0 Mustang Tech 2
T Drivetrain 1990 LX 5.0 Fox 5.0 Mustang Tech 1
6 1990 Speedo Gear Sleeve 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 1
R Electrical 1990 airbag module Fox 5.0 Mustang Tech 14
B 1990 On3 Turbo Build/Review 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 24
S 1990-Camshaft alignment 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 7
Z 1993 5.0HO swap in a 1990 F-150 surging problem Other Auto Tech 7
S Engine 1990 GT Alternator confusion Fox 5.0 Mustang Tech 15
Chieftain 1990 Mustang convertible power door window guide bar bushings. Bottom is replaceable, what about top Bakelite type? 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 8
90Hatchback Interior and Upholstery 1990 Mustang constant hot to radio (premium sound) Fox 5.0 Mustang Tech 23
T Engine 1990 5.0- Overheating and Smoke after Head Swap (Need advice ASAP) Fox 5.0 Mustang Tech 3
Ultra90GT Engine 1990 Opinions on camshaft Fox 5.0 Mustang Tech 4
R Electrical 1990 lx - TFI module failure? Fox 5.0 Mustang Tech 4
B Electrical 1990 - driver side door lock not working Fox 5.0 Mustang Tech 10
1 96 3.8 T5 to 1990 5.0 Fox 5.0 Mustang Tech 3
B 1990 GT. With a 5 lug/brake upgrade, can I fit 18x9" wheels? What suspension mods would I have to consider. (Thanks in advance!) 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 7
B Brakes 1990, low coolant light riddle Fox 5.0 Mustang Tech 10
9 Engine 1990 5.0 manual crank/no start Fox 5.0 Mustang Tech 11
G 1990 F150 Lariat. Pilot bearing stuck Other Auto Tech 4
S New to The Form, with a wrecked Mustang! The Welcome Wagon 3
P Paint and Body 1990 LX convertible need help identify "J" frames riveted to rocker panels Fox 5.0 Mustang Tech 6
Similar threads