Electronics Need help wiring something up? Thinking of adding an electrical component to your car? Need help troubleshooting that wiring glitch?

"INST LPS" fuse keeps blowing.

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Old Jul 8, 2007 | 09:29 PM
  #1  
facelessnumber's Avatar
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Car: 91 RS
Engine: L03 carbed
Transmission: 700R4, rebuilt+kit
Axle/Gears: 3.42, posi, disc
"INST LPS" fuse keeps blowing.

Tried a search, forgive me if this has been covered...

I just removed and reinstalled my dash pad, did some work on the e-brake... I know they were working last night, but today I have no gauge lights.

I have brake lights, tail, signal, flashers, dome, but no HVAC and no lights on the cluster.

The "INST LPS" fuse was blown. I replaced it, and didn't get so much as a flicker from the cluster before it blew again, instantly. Did that twice more then I noticed a pattern and stopped making burnt offerings to the fuse god.

I mention the work I was doing today because it's only logical to think it's something I did, but I'm having a hard time figuring out what. There's got to be a short somewhere and I'm going to have to track it down. Can I get some suggestions on where to start?

Thanks
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Old Jul 8, 2007 | 11:32 PM
  #2  
facelessnumber's Avatar
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Joined: Jun 2006
Posts: 130
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Car: 91 RS
Engine: L03 carbed
Transmission: 700R4, rebuilt+kit
Axle/Gears: 3.42, posi, disc
Re: "INST LPS" fuse keeps blowing.

Another development. The battery gauge isn't working either. Just that one. Other gauges in the cluster are fine. And for some strange reason my Summit digital air/fuel gauge is pegged. These things would seem completely unrelated if they didn't all happen at the same time!

It's getting too late to keep working on it, but so far my diagnostics have included blowing a bunch of fuses, and determining with my multimeter that both sides of the "INST LPS" fuse socket are grounded. I've also seen that the fuse doesn't blow until I turn on the lights, and if I have the dimmer all the way down it won't kill the fuse until I turn it up a bit. Of course at no point do the lights come on.

Thanks again for helping me figure this out. This is so annoying. Completely kills the satisfaction I got from finally looking at a dash with no cracks in it...
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Old Jul 9, 2007 | 02:20 AM
  #3  
Xophertony's Avatar
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From: Or-eh-gun
Car: 2012 Nissan Leaf
Engine: 80-kW AC synchronous electric motor
Transmission: Automatic
Axle/Gears: n/a
Re: "INST LPS" fuse keeps blowing.

well, first step is to pull the dash pad and see what wire you smashed. more then likely you have created a short in the courtesy power distribution to the cluster. since the volt gage gets it's reading from plugging in to your electrics this would explain why it's dead. and since this is tied into your cluster lights it would explain why the fuse does not blow until the lights are turned up from the most dim setting. (the most dim actually has the dash lights off BTW)

this is just my opinion of course.
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Old Jul 9, 2007 | 11:51 AM
  #4  
Fullsizewagon's Avatar
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From: Oslo, Norway
Engine: '85 Monte SS L69 305
Transmission: TH 200-4R
Axle/Gears: 3.23
Re: "INST LPS" fuse keeps blowing.

Xophertony has good points.
A trick to aid in locating shorts w/o keep blowing fuses, is to wire up a relatively high powered lamp (like brake/ turn/ main beam) to a couple of flat lug terminals. Put the terminals in instead of the fuse. The lamp will light fully as long as you have a short, and then you move wires and unscrew things until the lamp goes out (or dims considerably).
Be careful with the wattage in this case as your dash dimmer could burn out. Use a 21W bulb, and turn the dimmer up fully so the bulb gets bright.
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Old Jul 9, 2007 | 11:47 PM
  #5  
facelessnumber's Avatar
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Joined: Jun 2006
Posts: 130
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Car: 91 RS
Engine: L03 carbed
Transmission: 700R4, rebuilt+kit
Axle/Gears: 3.42, posi, disc
Re: "INST LPS" fuse keeps blowing.

Problem is fixed now, thanks for your help, guys. Sure was frustrating, but I learned a lot about how this dash is put together. Also discovered I needed to rework some of the Budweiser engineering that went into a previous owner's alarm install. The car is now better off for all this, and as a bonus the alarm actually works now!
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Old Jul 10, 2007 | 12:51 AM
  #6  
Xophertony's Avatar
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From: Or-eh-gun
Car: 2012 Nissan Leaf
Engine: 80-kW AC synchronous electric motor
Transmission: Automatic
Axle/Gears: n/a
Re: "INST LPS" fuse keeps blowing.

good on ya.

"budweiser engineering" i have never heard that before. funny.
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