Easy Project Gone Very Wrong
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Easy Project Gone Very Wrong
I had no instrument lights on my 1976 F250 so I thought I would change the bulbs. Little did I know that the whole backing plate would disintegrate. From there, I bought a new one from Carpenter and moved all of the bulbs. While I had everything apart I thought I would swap out the headlight switch as well. I did so and was really proud of my handy work. I put everything back together and couldn't wait to see all the instrument lights working. I re-connected the battery and turned the key on the ignition. The truck started cranking and then all of a sudden it stopped. There was total silence. No clicks, no cranks, no lights, nothing. I am now wondering where I start to try and troubleshoot the problem. Any ideas are sure welcome.
Hotshot
Joined: Apr 2009
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From: Stanley, VA
Go to the battery terminal side of the starter solenoid. There you'll find fusible links (at least one, I think the '76 has more than one). The wires that are fusible links will be tagged with a little plastic flag that says "FUSIBLE LINK" and then gives the gauge size of the link.
An easy way to test is to tug on the wire. If it feels soft or gives then the link is bad and needs to be replaced.
If it is a burned out link, you need to trouble shoot why it burnt out before you reconnect the battery.
An easy way to test is to tug on the wire. If it feels soft or gives then the link is bad and needs to be replaced.
If it is a burned out link, you need to trouble shoot why it burnt out before you reconnect the battery.
Postmaster
Joined: Sep 2013
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From: Pasadena, Ca
Im curious if you got the same instrument panel as you had, or you tried to get one different.
A good rule of thumb, disconnect the battery when you do electrical mods or changes. And only do one at a time then reconnect the battery and check your outcome before doing another project.
A good rule of thumb, disconnect the battery when you do electrical mods or changes. And only do one at a time then reconnect the battery and check your outcome before doing another project.
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
Originally Posted by phboyer
I had no instrument lights on my 1976 F250, so I thought I would change the bulbs. Little did I know that the whole backing plate (instrument cluster back) would disintegrate. From there, I bought a new (NOS) one from Carpenter and moved all the bulbs.
The factory installed instrument cluster backs were made of a composition material that can TURN TO DUST before your very eyes!
1981: FoMoCo came out with hard plastic cluster backs for Econolines that were also the service part replacements for these POS composition cluster backs.
E1PZ-10848-A .. Hard Plastic Cluster Back-Use with Oil & Amp Gauges / Obsolete
1975/79 F100/350 - 1975/91 Econoline - 1978/79 Bronco.
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E1PZ-10848-B .. Hard Plastic Cluster Back-Use with Oil & Amp Warning Lamps / Obsolete
1975/79 F100/350 - 1975/86 Econoline - 1978/79 Bronco.
Several years ago, Carpenter bought all of FoMoCo's remaining inventory of these cluster backs. So they're NOS, not repro's.
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The very first thing you always check is battery charge. Have a fully charged battery. So many people miss this first step. Then if fully charged check loose connections and grounds. Find a wiring diagram and if connections are good and clean battery charged check for voltage with dmm by touching an end of the wire with positive side dmm and ground with the black side of dmm. With this you want the key turned on but engine off. If needed better instructions hit me up.
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Thanks for the quick responses. I bought the back plate based on the number I go from Number Dummy in another link which was the same one with gauges. I re-used the plastic circuit board from the old backing panel.
I did disconnect the battery. However, I disconnected the negative side. Does this make a difference? I will check the fusible link now. I will also replace the battery with a new one just in case. I find it mysterious that the battery would go from good to bad at the same time I made the two changes I did. But, if that is the cause, I would be VERY happy. I don't have any power to the fuses now. I will check them all when I do.
I have one more question. What is the best way to find the root cause of this? I don't want to replace the fusible link only to have it fry again. Should I disconnect the harness at the light switch and instrument panels and plug one bask in at a time? Is there anything else I can do to identify the culprit?
I did disconnect the battery. However, I disconnected the negative side. Does this make a difference? I will check the fusible link now. I will also replace the battery with a new one just in case. I find it mysterious that the battery would go from good to bad at the same time I made the two changes I did. But, if that is the cause, I would be VERY happy. I don't have any power to the fuses now. I will check them all when I do.
I have one more question. What is the best way to find the root cause of this? I don't want to replace the fusible link only to have it fry again. Should I disconnect the harness at the light switch and instrument panels and plug one bask in at a time? Is there anything else I can do to identify the culprit?
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MSEE
Joined: Apr 2004
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From: Austin, TX
No need to replace it. The advice you were given was to check it, not replace it. In case it's not obvious, you need to pick up a multimeter if you don't have one already.
You can check continuity of a fusible link with a multimeter. I will note, however, that it takes a lot of current to pop a link. Even 16-gauge wiring can melt the insulation off itself before a link pops. Unless you got completely lost behind the instrument panel and managed to fuse out 10-gauge bus wiring, I'm guessing something else happened.
Post Fiend
Joined: Jan 2006
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From: Kasson, Minnesota
Make sure you check your battery with a mutimeter. It is very easy to get more involved than what has to be by doing some testing. I recently took my alternator off to redo some wiring and everything worked just fine when I stated. All I did was replace one wire and clean things up a bit. Went back to start the truck and nothing...not even a dome light. I rechecked wires and spent 30 minutes messing around until I grabbed a mutimeter to do a battery test and I had right about 10V. I put a jumper pack on it and I had power. My son loved to play in the truck so I figured he left key on or a door open and I didn't notice. Battery was dead enough to not give me anything. Not saying to ignore the wiring because that's absolute, but just making some simple tests first can help trouble shoot.
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You guys are great. The positive battery terminal post had some corrosion and the cable looked a little corroded and frayed. I removed the battery and cable and then used a multimeter to test all 4 fusible links. All had continuity. I went ahead and bout a new battery and cable. Low an behold the truck turned over and started. I then re-connected the new headlight switch. I got headlights. All was good. I then reconnected the harness for the instrument cluster. The good news is that I now have lights. The bad news is that the only gauge that works is the temperature gauge. Urrrrg. I don't really care about the oil pressure or voltage gauges but I need the gas gauge. Any thoughts on why only one of the four gauges would work?
MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
What you're calling a "voltage" gauge is actually a shunt ammeter. As long as it's pointing straight up, you're fine. That's all it will ever do. It's a show piece.
You will find ample troubleshooting information regarding the gas gauge using the forum's search tool; all steps apply to the oil pressure gauge as well.
You will find ample troubleshooting information regarding the gas gauge using the forum's search tool; all steps apply to the oil pressure gauge as well.
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Thanks for the help FMC. I read every post on the gas gauge and none of the seem to apply to mine. I have continuity on both of the posts and nuts on the back of gas gauge when I ground the other side. Doesn't that mean I am getting power to the gauge? Could it be that the gauge is bad? The plastic that surrounds one of the posts broke when I took it off when changing out the instrument cover back. It was working fine before that.
Hotshot
Joined: Apr 2009
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From: Stanley, VA
Thanks for the help FMC. I read every post on the gas gauge and none of the seem to apply to mine. I have continuity on both of the posts and nuts on the back of gas gauge when I ground the other side. Doesn't that mean I am getting power to the gauge? Could it be that the gauge is bad? The plastic that surrounds one of the posts broke when I took it off when changing out the instrument cover back. It was working fine before that.
If the gauge stays on empty then either the gauge is bad or there is a wiring problem.