santana82

Hi everyone,

I have a 82 Toyota pick up. The charge light is on and the Gauge fuse keeps blowing. I replaced the fuse, the light went off and the fuel pump gauge and water temp gauge corrected their reads. One drive around the block and boom, the light came back on, check the fuse box, the gauge fuse is blown and the gauges are reading low fuel (3/4 full tank) and warm water while the engine is normally hot. What should I check next?

2ToyGuy

Something in the circuit the Gauge fuse feeds has a short to ground, or near short. Try disconnecting the gauge cluster, which is the most likely location of the trouble, all the plugs that go to it, and see if the fuse still blows. I bet it won't. If it doesn't, you can either plug one plug at a time back into the gauge cluster, and when the fuse blows, see what all that particular plug feeds, and then see which gauge, light, etc, is shorted to ground. Lights can be tough to verify, as they have a very low resistance across to begin with. OR, you can take the gauge cluster, and check each gauge and light, one at a time, and see which has a short to ground.
Do you have a schematic for your gauge cluster? Do you have a multimeter to start testing things with? If not, go to Harbor Freight and pick one up. They're very inexpensive, and a meter is one of the best tools you can buy for working electrical problems of just about any kind.

BTW: You said a "fuel pump gauge"? I don't recall ever seeing a "fuel pump gauge". Did you mean a fuel pressure gauge? Is it aftermarket? If so, they generally, generally I say, are directly connected to the fuel system. No electrics, unless it has a light for night viewing. If it does, it will need to be checked for a short of some sort.

Does all that help at all?
Pat☺

santana82

Thank you Pat for helping me out. I, unfortunately, do not have a schematic for my gauge cluster. I was planning on looking up how to get to it. I do have a multimeter. One thing I noticed today that the voltage at the battery while the car is running and when pressing down on the gas pedal, the voltage keeps climbing and exceeds 15.2. I read somewhere that this is a sign of a bad voltage regulator. Could a bad voltage regulator cause the gauge fuse to blow and bring on the charge light? Just food for thought.

santana82

Sorry for the confusion. I meant fuel tank gauge. What is interesting is that when the gauge fuse is blow and the CHARGE light is on, the fuel tank gauge reads lower than normal as well as temperature lower than normal. The moment I replace the gauge fuse, both the fuel tank and temperature gauges start to correct rising up to what is normal.. that is until the fuse blows again and then they drop back to previous wrong reading. Does this mean that there is a short in both the temp and fuel tank systems?

2ToyGuy

OK, here we go!
If you look at the schematic above, which I found in the FSM for the 1983, bbut I am going to presume is either the same, or very close to, the 82 model, you can see the wire from the CHARGE fuse feeds one side of those 4 gauges. That's fairly self explanatory. NOW, why they go lower when the CHARGE fuse blows: Note the wire coming in the bottom of the 4 gauges from the ignitor. It essentially feeds a voltage to the tachometer that varies with engine speed. Why they made it go to the other gauges, I have no idea, but that varying voltage will make the gauges read something. It's a system where there are 2 voltages applied to the gauge set, and the "sum" of those two voltages, coupled with the resistance to ground from the sensors, make the gauges read what they read.

You can see that the CHARGE fuse feeds quite a few systems. Any one of them, the systems, could be the cause of the CHARGE fuse failing. It could be the gauges, the stop lights (not seen on this page), etc etc. I would say your best chance would be to Google, or whatever you use, the 82 or 83 FSM. Then, once you have the schematics, Look at every place the CHARGE fuse wire, the Yellow one, goes, and check them all for a short to ground. Especially an intermittent one.

Alternatively, you need to find out why the voltage out of the alternator gets so high. It could be that the supply to the CHARGE fuse is what's blowing it. That's entirely on the alternator, or at least the voltage regulator on it, anywho. Could the battery have a shorted cell? Does it get low just sitting with the engine off? Best way to test the battery is to take it to a chain auto parts store. Most of them will do a load test on your battery for free. They'll test out your alternator for free, as well.

Does all my rambling help any?
Pat☺

santana82

Pat, I wouldn’t call your replies rambling. More like wisdom pearls

I understand exactly your thought process. Now, I have a new voltage regulator in place. I popped in a new fuse, CHARGE light went off. I noticed the new fuse blew immediately the moment I shifted the gear to reverse. I took notice of that and wondered if the reverse light might havre something to do with it! Then to clear the doubt, I popped another new fuse and the moment I shifted to reveres it blew and the CHARGE light went back on! What do you think about that?

I took the battery to An auto chain store for testing as you recommended. This yellow wire you are talking about. You said it’s the CHARGE light. Why is it called CHARGE when it all it does is feed electric to lights, gauges and such?

thank you for your help! Much appreciated

2ToyGuy

My sincerest apologies. I wrote CHARGE when I should have said GAUGE fuse. I am sorry for the confusion.

Now then, that's about as clear as a San Francisco fog. On the reverse light. I'd say right off there's something in the reverse light circuit causing the fuse to blow. Generally, the case there is something in one of the reverse light fixtures back on the rear. They're part and parcel of the whole tail light assembly, but tyhe reverse lights are single bulbs in their own fixture in the tail light assembly. Chances are one of the hot wires feeding the reverse light bulbs has worn through, rubbing against where the tail light fixture mounts to the body. Check the two light fixtures, and trace the wires feeding the actual bulb mounts. Look for places the wire(s) have rubbed, or otherwise worn through and is (are) shorting to the body metal. I wager you'll find your trouble there.

Does that help at all?
Pat☺

santana82

Pat, you nailed it. I tinkered a little with the lights in the rear and that solved it. I didn’t find the culprit but I think moving the wires might have shifted the worn wire or something because I put a new fuse and it has survived Yee Pee Kay Yay!

Now farewell until the wire shorts again, but at least I know where it is and I can dig into it if it happens again. Thank you so much for all your help!