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Charlie don't surf..
'92 Ford Bronco XLT
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16,433 Posts
Discussion Starter · #1 ·
Hey guys, so two times in the last couple of months fuse 8 has blown..Both times I wasn't driving. First time, I went to pull out of my drive way after starting the engine and noticed the odo display was dead, and then today, I went to turn the engine on and same thing, no display..Swap in a 15 amp fuse and everything is good to go.

Checked all the usual suspects as detailed in Chilton's troubleshooting fuse 8 and I can't find any bare connections or obvious short to ground..No contact with screws to the dome light or chaffed wires by the visor screws. Thinking the drivers side dome light switch may be going bad, but that's just a guess..

Thoughts, suggestions before I start tearing s**t apart?

Short Circuits, Common Locations TSB 95-02-11 for 92-95 Bronco & F Series; SEE A - Poss. Short Locations: (I summarized all here; see TSB for more info incl location diagrams for each)
1. Driver's side A pillar trim screws may have been installed thru da 17K745 Sun Visor wire assy & .. bullet connector;
2. dome lamp screw;
3. Scuff plate screws (driver's side) may pinch the 14A504 wire assy;
4. Dash Harness 14401 wire assy may be trapped/pinched between Half car beam & instrument panel attachment (repeated as #7. the wire harness may be pinched/shorted behind the dash where the 14401 wire assy may come in contact w/a sharp edge on dash panel wall;
5. shift cable assy near tranny may chaf the wire harness; the wire harness;
6 is for manual tranny - harness chaf at clutch pedal;
7. repeated above..brake pedal-to-dash panel wall weld
; dome, vanity, map & cargo lights; engine & glove compartment lamps; power mirrors; remote keyless entry system & odometer & fuse 8 blows) ETC. in 94-95..."
Source: by Ford via Chilton
 

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Intermittent shorts are the most difficult thing in electronics
Sounds like you know the circuit better than we do and have a likely list of suspects you have already checked
How FREQUENTLY does the problem happen (pls dont say once a month....)
Cut out the dome light entirely for a while and see if problem goes away?
 

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'92 Custom w/ '95 MAF 5.0 M/T, 33's, 4.10 LSD
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The timing could be coincidental, but it seems like a power surge of some sort at start-up.

As far as dome light stuff, mine was increasingly problematic until I found that one of the two green/yellow lines (they seem to be redundant, almost like Ford knew they would rot out) through the driver's door sill was barely hanging on by a thread. Something like that could perhaps be acting as a grounded wire, if a few of them in the bundle are similarly decayed.
 

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Yo LTC Bill Kilgore,

Yo Mesa,
In addition to Common Locations for Short Circuits TSB 95-02-11 in 94-95 Bronco & Trucks; Source: by Ford; WIRING - SUMMARY OF POSSIBLE LOCATIONS OF SHORTS Uz4aCpJyaaA==

Cab Fuse 8;
Some customers may have concerns that the following features are inoperative or have voltage drain:
All courtesy lamps
Map lamps
Engine compartment lamp
Glove compartment lamp
Speedometer/Odometer (Programmable Speedometer Odometer Module (PSOM) in the instrument cluster
Dome lamp
Power mirrors
Lighted vanity
Cargo lamp
Remote Keyless Entry (RKE)

This is due to insufficient clearance between the outer roof panel of the cab and a map/dome lamp mounting screw, causing a short in Circuit 54, which causes Fuse 8 (15 amp) to become inoperative. This fuse protects the wiring for the above vehicle features.
Replace existing dome mounting screws with new, shorter screws. Refer to the following procedure for service details.
BACKGROUND
Three screws are required to mount the map-dome lamp to the inner roof panel of the cab. Two (2) of the three (3) screws are used to complete two electrical circuits, 53 and 54. Circuit 53 is after the lamp switches and is "cold" ("cold" means that 12 volts are not present) & Circuit 54 is before the lamp switches and is "hot" at all times ("hot" means that there are always 12 volts present).
The 52814-S36 screw is approximately 25.4mm (1") long. When there is a sufficient amount of downward force applied to the outer roof panel of the cab, the panel will make contact with the screw that has Circuit 54 (12 volts) on it.
For example: When the brushes and dryer pass over the roof of the truck in a car wash or when traveling at highway speeds. As the roof panel contacts the screw, it causes a direct short-to-ground. When this occurs, Fuse 8 will be overloaded (15 amp), open and disable the listed features.
SERVICE PROCEDURE:
1. Carefully pry pillar/dome lamp lens from interior lamp body.
2. Remove screws retaining interior lamp (map/dome) to roof trim panel.
3. Install new screws (52802-S36, 19mm).
NOTE: ANOTHER OPTION WOULD BE TO REMOVE OLD SCREWS AND CUT/GRIND APPROXIMATELY 6.35mm (1/4") OFF THE END AND REINSTALL.
4. Reinstall pillar/dome lamp lens

52802-S36B Screw, 19mm

Or, these conditions may be caused by trim screws installed through the 17K745 sun visor wire between the left hand "A" pillar and the left hand visor bullet connector.
ACTION: Tape the damaged or exposed wire conductor and add scrolling to protect the wiring from trim screw shorts. Refer to the following service procedures for service details.
SERVICE PROCEDURE
1. Remove the garnish moulding. Refer to the 1994 Econoline, F-150-350, Bronco F-Super Duty Service Manual, Page 01-05A-5, for the removal procedure.
a. Inspect the wiring condition against the trim screws.
b.Check screws for burn marks.
2. If burn mark is found, use electrical tape to protect exposed/damaged wire. Add 1/4" (6.35 mm) scrolling to maximize protection.
3. Replace #8 fuse.

Scuff plate screws (driver's side) may pinch the 14A504 wire assy;
4. Dash Harness 14401 wire assy may be trapped/pinched between Half car beam & instrument panel attachment (repeated as #7. the wire harness may be pinched/shorted behind the dash where the 14401 wire assy may come in contact w/a sharp edge on dash panel wall;
5. shift cable assy near tranny may chaf the wire harness; the wire harness;
6 is for manual tranny - harness chaf at clutch pedal;
7. repeated above..brake pedal-to-dash panel wall weld"

As jowens1126 wrote, " Underhood lamp. They tend to corrode very badly. I suppose its possible for it to short out however unlikely."
"The one my money is on is the RKE Box.
I have had issues with mine in the past multiple times.
I have also scoured the junk yards over the years looking for them in Bronco's.
Every single one I have found was shorted out the same way.
If you remove the RKE Module from under the dash and open it up, you will likely find this short circuit....

If pic doesn't appear, see it @ http://www.supermotors.net/getfile/1117290/fullsize/20170611_210200.jpg
The pancake capacitor overheats and melts the ribbon cable.
It could either fuse 2 wires in the cable together or bare wire contact the diode that sticks up into the bottom of the ribbon cable.
If yours is the same, I would replace it with one from a 95 SN95 Mustang. They dont have that type of capacitor and thus wont fail that way.
It is exactly the same as the one in the bronco so everything will work perfectly. Its even the same part number. You can find them on ebay pretty cheap.
Note SN95 under the barcode...."
 

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Charlie don't surf..
'92 Ford Bronco XLT
Joined
·
16,433 Posts
Discussion Starter · #5 ·
Intermittent shorts are the most difficult thing in electronics
Sounds like you know the circuit better than we do and have a likely list of suspects you have already checked
How FREQUENTLY does the problem happen (pls dont say once a month....)
Cut out the dome light entirely for a while and see if problem goes away?
I know, I've had a few intermittent shorts over the year and their a PITA..Like I said it's happened twice in the last few months. Except for weekends, the Bronco doesn't get driven all that much..I really don't think the issue is with the dome light, but that's not a bad idea.
 

·
Charlie don't surf..
'92 Ford Bronco XLT
Joined
·
16,433 Posts
Discussion Starter · #6 ·
Yo LTC Bill Kilgore,

Yo Mesa,
In addition to Common Locations for Short Circuits TSB 95-02-11 in 94-95 Bronco & Trucks; Source: by Ford; WIRING - SUMMARY OF POSSIBLE LOCATIONS OF SHORTS Uz4aCpJyaaA==

Cab Fuse 8;
Some customers may have concerns that the following features are inoperative or have voltage drain:
All courtesy lamps
Map lamps
Engine compartment lamp
Glove compartment lamp
Speedometer/Odometer (Programmable Speedometer Odometer Module (PSOM) in the instrument cluster
Dome lamp
Power mirrors
Lighted vanity
Cargo lamp
Remote Keyless Entry (RKE)

This is due to insufficient clearance between the outer roof panel of the cab and a map/dome lamp mounting screw, causing a short in Circuit 54, which causes Fuse 8 (15 amp) to become inoperative. This fuse protects the wiring for the above vehicle features.
Replace existing dome mounting screws with new, shorter screws. Refer to the following procedure for service details.
BACKGROUND
Three screws are required to mount the map-dome lamp to the inner roof panel of the cab. Two (2) of the three (3) screws are used to complete two electrical circuits, 53 and 54. Circuit 53 is after the lamp switches and is "cold" ("cold" means that 12 volts are not present) & Circuit 54 is before the lamp switches and is "hot" at all times ("hot" means that there are always 12 volts present).
The 52814-S36 screw is approximately 25.4mm (1") long. When there is a sufficient amount of downward force applied to the outer roof panel of the cab, the panel will make contact with the screw that has Circuit 54 (12 volts) on it.
For example: When the brushes and dryer pass over the roof of the truck in a car wash or when traveling at highway speeds. As the roof panel contacts the screw, it causes a direct short-to-ground. When this occurs, Fuse 8 will be overloaded (15 amp), open and disable the listed features.
SERVICE PROCEDURE:
1. Carefully pry pillar/dome lamp lens from interior lamp body.
2. Remove screws retaining interior lamp (map/dome) to roof trim panel.
3. Install new screws (52802-S36, 19mm).
NOTE: ANOTHER OPTION WOULD BE TO REMOVE OLD SCREWS AND CUT/GRIND APPROXIMATELY 6.35mm (1/4") OFF THE END AND REINSTALL.
4. Reinstall pillar/dome lamp lens

52802-S36B Screw, 19mm

Or, these conditions may be caused by trim screws installed through the 17K745 sun visor wire between the left hand "A" pillar and the left hand visor bullet connector.
ACTION: Tape the damaged or exposed wire conductor and add scrolling to protect the wiring from trim screw shorts. Refer to the following service procedures for service details.
SERVICE PROCEDURE
1. Remove the garnish moulding. Refer to the 1994 Econoline, F-150-350, Bronco F-Super Duty Service Manual, Page 01-05A-5, for the removal procedure.
a. Inspect the wiring condition against the trim screws.
b.Check screws for burn marks.
2. If burn mark is found, use electrical tape to protect exposed/damaged wire. Add 1/4" (6.35 mm) scrolling to maximize protection.
3. Replace #8 fuse.

Scuff plate screws (driver's side) may pinch the 14A504 wire assy;
4. Dash Harness 14401 wire assy may be trapped/pinched between Half car beam & instrument panel attachment (repeated as #7. the wire harness may be pinched/shorted behind the dash where the 14401 wire assy may come in contact w/a sharp edge on dash panel wall;
5. shift cable assy near tranny may chaf the wire harness; the wire harness;
6 is for manual tranny - harness chaf at clutch pedal;
7. repeated above..brake pedal-to-dash panel wall weld"

As jowens1126 wrote, " Underhood lamp. They tend to corrode very badly. I suppose its possible for it to short out however unlikely."
"The one my money is on is the RKE Box.
I have had issues with mine in the past multiple times.
I have also scoured the junk yards over the years looking for them in Bronco's.
Every single one I have found was shorted out the same way.
If you remove the RKE Module from under the dash and open it up, you will likely find this short circuit....

If pic doesn't appear, see it @ http://www.supermotors.net/getfile/1117290/fullsize/20170611_210200.jpg
The pancake capacitor overheats and melts the ribbon cable.
It could either fuse 2 wires in the cable together or bare wire contact the diode that sticks up into the bottom of the ribbon cable.
If yours is the same, I would replace it with one from a 95 SN95 Mustang. They dont have that type of capacitor and thus wont fail that way.
It is exactly the same as the one in the bronco so everything will work perfectly. Its even the same part number. You can find them on ebay pretty cheap.
Note SN95 under the barcode...."
Thanks Al..I've gone through most of that..No RKE on my rig, so I can eliminate that fully from the equation.

I have the later model dome light and pulled that again yesterday..there's no way the screws are touching the roof..They're not even close..I guess if someone was up there jumping on the roof that's possible, but that's not happening that I'm aware of.

Same with the visor, the screws there aren't coming into contact with anything..

I'll keep looking.
 
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95 f-150 4x4 5.8 e4od 05 F250 axles w/4:10's lifted/modded owned since 97 w/28K
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not sure if its related to your problem but, i had a bunch of electrical issues one time with my electric mirrors and such and ended up being a huge ground junction under the dash, kinda in the middle. somehow the junction got shorted and melted and was no longer grounding many things on the truck, i don't remember how many wires are crimped together but there was a bunch
 
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Charlie don't surf..
'92 Ford Bronco XLT
Joined
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16,433 Posts
Discussion Starter · #8 ·
not sure if its related to your problem but, i had a bunch of electrical issues one time with my electric mirrors and such and ended up being a huge ground junction under the dash, kinda in the middle. somehow the junction got shorted and melted and was no longer grounding many things on the truck, i don't remember how many wires are crimped together but there was a bunch
I'll take a look, but I'd expect if I had problem like that the fuse would pop all of the time..
 

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Yo Jer,
In event you don't have the 92 Fuse Block & PDB info to narrow downthe probable perpetrators:
Font Material property Pattern Parallel Design

- fuse H is a MAXI by former member Steve83
 
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