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Resolved Windshield wiper troubleshooting - Wiper turns OFF when Headlights turned ON

  • Thread starter Thread starter afjLX
  • Start date Start date Feb 9, 2025
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Feb 9, 2025
#1
  • Feb 9, 2025
  • #1
Ok, on to the next issue on my 1987 fox and starting this thread for help. The windshield wipers come on but shut off when the headlights are turned on. Bad news is this 1987 was a 4cyl to 5.0 swap. So wiring could be the culprit. Posting here to see if anyone has seen this issue before in general? I'm about to start digging through the 1987 EVTM.

Some things I had questions on and things to note:

  1. Just using the headlights by themselves -> whenever I turn the headlights OFF, a chime rings is that normal? When this chime rings after turning OFF the headlights, the warning indicators on the bottom right (1987 cluster) all come on - I'm guessing this not normal
  2. Wipers come on but speed adjustment on stalk doesn't do anything. Turning on the headlights stops the wiper even if the wiper switch is on.
  3. The Multifunction switch appears to be new. Anyone hear of the wrong MFS causing this issue?

I'm leaning towards the MFS being an issue or wiring there as an issue. Thoughts?

*UPDATE FIX*

Well finally was able to dedicate some time to this. Found the issue was a bad ground at wipe wiper motor. Ran a separate ground to the the shock tower and all is well now. All speeds work.
 
Last edited: Mar 27, 2025

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
28,021
10,646
213
polk county florida
Feb 10, 2025
#2
  • Feb 10, 2025
  • #2
Pull the MFS and look for a part number
 
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Feb 10, 2025
#3
  • Feb 10, 2025
  • #3
General karthief said:
Pull the MFS and look for a part number
Click to expand...
Good idea. Hopefully there is a PN stamped on it somewhere.
 
Reactions: General karthief

89notchDude

Active Member
Apr 11, 2022
84
42
28
central NJ
Feb 11, 2025
#4
  • Feb 11, 2025
  • #4
Interesting bc I have an 89 4 cyl to 5.0 car and my wipers and chime dont work and once the key is in the run position, the front parking lights are always on no matter if the switch is on or off. I installed a new headlight switch and turn signal switch. Something is crossed. I will be following this thread.
 
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Mar 27, 2025
#5
  • Mar 27, 2025
  • #5
afjLX said:
Ok, on to the next issue on my 1987 fox and starting this thread for help. The windshield wipers come on but shut off when the headlights are turned on. Bad news is this 1987 was a 4cyl to 5.0 swap. So wiring could be the culprit. Posting here to see if anyone has seen this issue before in general? I'm about to start digging through the 1987 EVTM.

Some things I had questions on and things to note:

  1. Just using the headlights by themselves -> whenever I turn the headlights OFF, a chime rings is that normal? When this chime rings after turning OFF the headlights, the warning indicators on the bottom right (1987 cluster) all come on - I'm guessing this not normal
  2. Wipers come on but speed adjustment on stalk doesn't do anything. Turning on the headlights stops the wiper even if the wiper switch is on.
  3. The Multifunction switch appears to be new. Anyone hear of the wrong MFS causing this issue?

I'm leaning towards the MFS being an issue or wiring there as an issue. Thoughts?
Click to expand...


Well finally was able to dedicate some time to this. Found the issue was a bad ground at wipe wiper motor. Ran a separate ground to the the shock tower and all is well now. All speeds work.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
28,021
10,646
213
polk county florida
Mar 27, 2025
#6
  • Mar 27, 2025
  • #6
All is well with a random wire hang'n out under the hood..... I hate to see that, looked into tracing the proper ground wire for the issud?
 
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Mar 27, 2025
#7
  • Mar 27, 2025
  • #7
General karthief said:
All is well with a random wire hang'n out under the hood..... I hate to see that, looked into tracing the proper ground wire for the issud?
Click to expand...
It’s hard to see. It’s black and a very short run under the bundle that goes into the firewall. Looks factory. The only thing that bothers me is the yellow eyelit crimp I used. But I mounted at the back where it is not visible.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,351
21,547
234
Box behind Walmart
Mar 29, 2025
#8
  • Mar 29, 2025
  • #8
afjLX said:
*UPDATE FIX*

Well finally was able to dedicate some time to this. Found the issue was a bad ground at wipe wiper motor. Ran a separate ground to the the shock tower and all is well now. All speeds work.
Click to expand...

Rookie

That's what [Resolved] buttons and last posts are for.
 
Reactions: afjLX
A

afjLX

Member
Nov 16, 2024
83
20
18
DFW,TX
Mar 30, 2025
#9
  • Mar 30, 2025
  • #9
Noobz347 said:
Rookie

That's what [Resolved] buttons and last posts are for.
Click to expand...
lol I had no idea. I selected resolved
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,351
21,547
234
Box behind Walmart
Mar 30, 2025
#10
  • Mar 30, 2025
  • #10
afjLX said:
lol I had no idea. I selected resolved
Click to expand...

You un-resolved it again.

I in-turn re-resolved it.

Glad we got [that] resolved.

 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
28,021
10,646
213
polk county florida
Mar 30, 2025
#11
  • Mar 30, 2025
  • #11
Now I'm REALLY confused
I know , what's new?
 
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