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| Shorted the Dash lights and guages https://slantsix.org/forum/viewtopic.php?t=39063 |
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| Author: | 1974stepside [ Sat Feb 20, 2010 10:39 am ] |
| Post subject: | Shorted the Dash lights and guages |
I did the 7805 conversion then read a posting where it says the readings will be incorrect due to the 1v difference in the original system and doing the 7805 5v mod. anyway I orderred the solid state limiter. The problem I have is that when I was removing the cluster to get to the 7805 regulator it touched metal on the dash and shorted one of the tail lights, dash lights and guages (I know, very stupid, im a noob). I put in the solid state limiter and get the lights blinking behind it but do not know what to do. I replaced the tailight that blew but now I want the guages etc to work any ideas on how to proceed? The tail lights, indicators, head lights, brake lights work. The dash lights, fuel, temp guages do not. Sorry for the long posting. This is the other forum where Ronny B's posting made sense to go with the solid state limiter: http://www.forabodiesonly.com/mopar/sho ... hp?t=75065 |
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| Author: | SlantSixDan [ Sat Feb 20, 2010 12:05 pm ] |
| Post subject: | |
You had the battery hooked up while you were R&Ring the instrument cluster, it sounds like, is that correct? |
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| Author: | 1974stepside [ Sat Feb 20, 2010 12:41 pm ] |
| Post subject: | |
Yes. Any idea of what to do? |
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| Author: | SlantSixDan [ Sat Feb 20, 2010 12:46 pm ] |
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Get these three books and read them before attempting further repairs. |
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| Author: | 1974stepside [ Sat Feb 20, 2010 1:03 pm ] |
| Post subject: | |
I have the Haynes manual for my year and a couple of other books. Just looking for advice from anyone who ran into similar issue. Thanks, I will look into the others. |
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| Author: | SlantSixDan [ Sat Feb 20, 2010 1:31 pm ] |
| Post subject: | |
The Haynes manual will get you into trouble more than it will help you. My main point — and I don't mean to slam you here — is that if you did not know better than to make such a major, basic, dangerous error, you are setting yourself up for serious injury and/or damage to your truck if you continue trying to do your own work without getting some education first. |
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| Author: | 1974stepside [ Sat Feb 20, 2010 9:29 pm ] |
| Post subject: | |
Yes, it was a silly mistake having the battery connected while tooling around in the dash. This is my daily driver and was hoping someone would know why it is only the dash and guages and how I can resolve it. For the price of some of those books I can take a course or pay somebody to fix this issue. Thanks anyway. |
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| Author: | Eric W [ Sat Feb 20, 2010 9:58 pm ] |
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Sounds like you got full power (12V instead of the 5V the limiter supplies)to your guages. They probably went bye bye..ie, fried. You'll need some new (read: wrecking yard) guages. Don't know about the dash lights..maybe a fuse? |
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| Author: | 1974stepside [ Mon Feb 22, 2010 10:05 am ] |
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Strange, the guages still work. I put it back to using the radio shaq parts http://www.allpar.com/history/mopar/electrical2.html and the guages actually work. stumped. |
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| Author: | KBB_of_TMC [ Tue Feb 23, 2010 9:04 am ] |
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If you have a poor instrument cluster ground, it might work well enough for the regulator to work OK, but not well enough for the dash lights to easily be seen. Sometimes, it's worth running a ground wire just to ensure you've got a good ground. |
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| Author: | 1974stepside [ Tue Feb 23, 2010 11:38 am ] |
| Post subject: | |
Are you saying run a ground wire from the back of the instrument cluster? |
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| Author: | 1974stepside [ Mon Mar 08, 2010 11:34 am ] |
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Quote: If you have a poor instrument cluster ground, it might work well enough for the regulator to work OK, but not well enough for the dash lights to easily be seen. Sometimes, it's worth running a ground wire just to ensure you've got a good ground.
SOme wires at the bulkhead in the cab are fried and the previous owner butchered some of the wiring putting in a radio. The Negative black power wire from the instrument cluster is just taped off. if I replace it where should this wire go? Truck runs fine except for the dash light, guages and the right indicator seems to blow everytime its replaced. any ideas? not sure that I can afford a painless wire harness. |
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| Author: | KBB_of_TMC [ Mon Mar 08, 2010 2:14 pm ] |
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Please let me echo Dan's comments. Do yourself a favor and get the factory schematics - make a copy and update the copy with what you actually find. A heavy black wire is probably a main 12V power feed, often off the ammeter - don't connect it anywhere if you aren't sure what you're doing as it is likely not fused except via the fusible link (if you still have one!) and could do a lot of damage. If you have a full current ammeter (used in trucks at least up to '77, cars up to '74, I think), the wiring to it often gave problems at the bulkhead and so got bypassed. Typically two large wires (typically 1 red and 1 black) went to the ammeter; both were hot and unfused (except via the fusible link) - one to the battery side and one to the alternator side. Generally (there are some exceptions), grounds to the dash are made by screws and *NOT* by wires . Unfortunately, wiring harnesses often get abused by those who don't understand what they're doing and repairs are often shoddy. If you must start poking around w/o schematics, put an old headlight in *series* with the battery. That will let you measure voltages OK, but even if you short something out the current will be limited to a fairly safe value (5A or so). You parking lights, etc. ought to work enough for testing. Be aware that 5A is plenty to destroy gauges. The dash lights and gauges get their power via different routes; since they both quit either both paths were damaged or their common ground is incomplete. The dash ground for the dash lights and gauges wasn't designed for a huge current, so it's possible the contacts there or any PC board traces have been burned out. Fortunately, it ought to be easy to see if that's your problem. If you can get at the back of the dash, (do the current limiting trick above), poke around with a 12V test light to any instrument light ground - if you get any significant voltage there, your dash isn't grounded properly. |
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| Author: | 1974stepside [ Mon Mar 08, 2010 2:37 pm ] |
| Post subject: | |
poke around with a 12V test light to any instrument light ground - if you get any significant voltage there, your dash isn't grounded properly. Yes when I do touch on the dash cluster circuit board i get light and I believe around 12v with the key in the on position. Ordered 2 books, still looking for a good manual for my year/model. I know I should probably have the truck rewired but am trying to postpone that until I have time/money. |
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| Author: | KBB_of_TMC [ Mon Mar 08, 2010 3:58 pm ] |
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If you're sure you've got ~12V at what ought to be ground, you can try running a wire from there to a good body ground. Keep the current limiting light in place in series with the battery and see if the dash lights work OK (dim is fine)- if they do, you can remove the current limiting light and see if everything works again. |
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