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Request for help with electrical problem

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Old 01-14-2019, 04:11 AM
holger100
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Request for help with electrical problem

Hello,
I hope someone can help me.

I'm setting myself up for a Ford F-100 (1978, V8 5.0L, 302cui) and am currently standing with a big question mark in my face.

My problem: The instrument lighting is working only partially.
The light or bulbs for safety belts, handbrake, high beam, turn signals on the left and right, windscreen wipers and driving lights and the lighting from the heating unit work.
It does not work: Oil gauge lighting, fuel gauge, speedometer, battery gauge and engine temperature gauge.

What I could exclude:
- All bulbs of the instrument unit replaced by new ones (also versions cleaned)
- fuse works (it is fine and otherwise the other lights would not go)
- Plug in the unit (on the back) seems to be in order and has also locked in

Did I miss something? Could the "board" (cluster at the back) at the back have a defect? Or is there a special trick?

Already thank you for accepting my problem.
 
  #2  
Old 01-14-2019, 01:56 PM
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The back of the cluster can crumble, causing the bulb holders to not go in tightly, and losing contact.

Your light switch could be the problem too. And don't forget that the **** can be turned to change the brightness, so it might be all the way at dim, if you're lucky.

Are your heater controls and the indicators for the headlight and wiper controls lighting up? They're supposed to light up with the gauge lights.
 
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Old 01-14-2019, 02:42 PM
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Originally Posted by holger100 View Post
I'm setting myself up for a 1978 F-100 and am currently standing with a big question mark in my face. My problem:

The instrument lighting is working only partially. The light or bulbs for safety belts, handbrake, high beam, turn signals on the left and right, windscreen wipers and driving lights and the lighting from the heating unit work.

It does not work: Oil gauge lighting, fuel gauge, speedometer, battery gauge and engine temperature gauge.

What I could exclude:

All bulbs of the instrument unit replaced by new ones (also versions cleaned) / Fuse works (it is fine and otherwise the other lights would not go).

Plug in the unit (on the back) seems to be in order and has also locked in

Did I miss something? Does the "board" (cluster back) have a defect?
YES!
1975/79 F100/350; 1975/80 Econoline; 1978/79 Bronco:

The instrument cluster backs were made of a composition material that can TURN TO DUST before your very eyes!

1981: Ford came out with hard plastic cluster backs for Econolines. These were also the "service part replacements" for the POS composition cluster backs.

There are TWO types, both are obsolete. CARPENTER NOS OBSOLETE PARTS in Concord NC has both of them (dennis_carpenter.com .. 704-786-8139).

E1PZ-10848-A .. Hard Plastic Cluster Back - Use with Oil/Amp GAUGES / Obsolete

1981/91 Econoline / Retrofit: 1975/79 F100/350; 1975/80 Econoline; 1978/79 Bronco.
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E1PZ-10848-B .. Hard Plastic Cluster Back - Use with Oil/Amp WARNING LAMPS / Obsolete

1981/86 Econoline / Retrofit: 1975/79 F100/350; 1975/80 Econoline; 1978/79 Bronco.
 
  #4  
Old 01-14-2019, 03:04 PM
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Holger:
If the above solutions don't correct your problem...this may be a stretch but I have a 66 that had a similar issue. I know the year is different, but Ford kept a lot of the wiring similar year to year. Check your ground at the ignition switch and your 12v power supply at the ignition switch. I think that the items you mention get either a ground or power through the switch, so make sure the ignition housing is getting ground and that the wires coming from the back of the ignition switch are all "hot". The items you mention all have a "common denominator".
 
  #5  
Old 01-14-2019, 03:54 PM
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You might also try cleaning the copper "runs" where the bulb holders make contact on the back of the printed circuit with a pencil eraser.
 


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