I have the 7.5 amp gauge fuse blowing after about 20 minutes. All gauges are indicating normally before it blows. I'm not very electrically inclined at all so if I check the resistance on the back of the combination meter per the FSM should I see something abnormal? Has anyone had something similar and there might be a fairly common cause for this?
Gauges fuse blowing
- Thread starter AA996
- Start date
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dgangle
total rice
read this similar thread a from a couple weeks ago. https://forum.ih8mud.com/40-55-series-tech/348295-fuse-keeps-blowing.html
The very first thing you need to do is get a wiring diagram specific for your vehicle. Buy a FSM if no one offers it up here. Then buy a multimeter and learn how to use it.
then start unhooking things and measuring resistance.
by chance have you recently installed anything electrical such as lights, stereo, etc or had any recent body damage???? if so start isolating these areas first.
...and no there is no magic wand or silver bullet. Diagnosing these types of thing can be frustrating and takes some time and thought.
The very first thing you need to do is get a wiring diagram specific for your vehicle. Buy a FSM if no one offers it up here. Then buy a multimeter and learn how to use it.
then start unhooking things and measuring resistance.
by chance have you recently installed anything electrical such as lights, stereo, etc or had any recent body damage???? if so start isolating these areas first.
...and no there is no magic wand or silver bullet. Diagnosing these types of thing can be frustrating and takes some time and thought.
- Thread starter
- #3
Thanks dgangle. I have a FSM and a multimeter. The only thing I've done to the Cruiser recently was change the thermostat. Perhaps I disturbed the wiring for the water temp sensor - I'll start there. I guess the thing that stumps me is I would suspect that if there was a short it would make an erronious indication on the gauge. All gauges look normal right until the fuse blows.
dgangle
total rice
you have the tools then, get to it. Start eliminating things in that circuit until you find the culprit.
- Thread starter
- #6
Well, I put in a new fuse, a 10 amp vs. the 7.5 that normally is installed there. Our little store only had the 10a fuse. Anyway, the gauge cluster has been operating fine now for two weeks, all resistance checks as per the FSM. Weird.
I love a problem that fixes itself, but I suspect it'll show itself again sometime.....
Thanks everyone for your help!
I love a problem that fixes itself, but I suspect it'll show itself again sometime.....
Thanks everyone for your help!
Putting in a larger fuse is masking the problem. Toyota would have designed the circuit protected by the 7.5 amp fuse to be operating well below that normally. So odds are that your present operating current is probably double what is normal. So you should really continue to troubleshoot the problem. Put your ammeter in series with the fuse and start disconnecting things on that circuit. When you disconnect something and see a big drop in current, you are probably getting warm.
EDIT: After thinking about this a little while, you can remove the fuse, switch your multimeter in 10 amp Ammeter function and substitute it in place of the fuse. Now your ammeter is in the circuit measuring total current at the fuse. You will note (looking at the schematic in the FSM) that this fuse powers more than just the instrument cluster. A leg goes off to other places like the check engine light in schematic 1 section 4, the charge warning light schematic 1 section 6, etc. Start disconnecting these circuits and watch for the big drop in current. It may take awhile, but you'll find it. Better to be doing this in the relative comfort of your garage than out on the trail somewhere. One of the circuits powered by the 7.5 amp fuse is the IG Main Relay coil, so bad things are going to happen if this fuse blows (but you already know that).
EDIT: After thinking about this a little while, you can remove the fuse, switch your multimeter in 10 amp Ammeter function and substitute it in place of the fuse. Now your ammeter is in the circuit measuring total current at the fuse. You will note (looking at the schematic in the FSM) that this fuse powers more than just the instrument cluster. A leg goes off to other places like the check engine light in schematic 1 section 4, the charge warning light schematic 1 section 6, etc. Start disconnecting these circuits and watch for the big drop in current. It may take awhile, but you'll find it. Better to be doing this in the relative comfort of your garage than out on the trail somewhere. One of the circuits powered by the 7.5 amp fuse is the IG Main Relay coil, so bad things are going to happen if this fuse blows (but you already know that).
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- Thread starter
- #8
Good idea to use the ammeter as a fuse. I didn't think of that. I'm here in Ft. Lauderdale so I'll load up on 7.5 fuses and when I go back to Cuba I'll use the ammeter trick. I would like to find the culprit before something worse happens. Thanks!
