The temp gauge pegs all the way to H when the ignition is turned on in my 87 sammy....what gives?

It's probably a faulty wire somewhere, but I'm pretty sure I didn't screw with that wire.

The temp gauge pegs all the way to H when the ignition is turned on in my 87 sammy....what gives?

It's probably a faulty wire somewhere, but I'm pretty sure I didn't screw with that wire.

Other than stating that this is not a common problem, I can only say that the truck is 23 years old and stuff like that should be expected.

I would start my trouble-shooting by a visual inspection of the dash temperature sender by the thermostat housing.

For detailed information and testing procedures, download a Samurai Factory Service Manual (fsm) - available at several places of the Internet.   I can think of a real handy one.  A link to it is in my signature... 

You might start by pulling the wire off the sender, and using an ohm
meter to see if there is a really high reading on the wire and then on
the sender, this might rule out a bad sender and save chasing wires,
one of my favorites 

Word.  I unplugged a bunch of crap when I was re-wrapping the wires so I probably forgot to plug it in 

I'll check it out and report back.

Ack, I have an FSM, just didn't feel like looking at it. 

Word.  I unplugged a bunch of crap when I was re-wrapping the wires so I probably forgot to plug it in 

If I recall correctly, leaving the sender unplugged results in the gauge staying at cold, if yours is pegged at hot, you've probably got the wire shorted to ground or connected to the wrong sensor.

Of course I could verify by checking the FSM, rather than going from memory, but, it's downstairs, and I'm too lazy to get it 

I'm with you Fordum, I'm too lazy to even respond to this.

Buttholes 

Alright so I checked the resistance at the sender and it's 55 ohms. 

A new problem cropped up too, when I turn off the switch the dome light flashes once quickly and so does the high indicator in the cluster.

Alright so I checked the resistance at the sender and it's 55 ohms. 

mmm - wonder what it should be - - I know I can find that out by checking the FSM, but I'm too lazy 

More to the point - if you check my previous post, you'll see I suspect the problem to be a short to ground, and if that's the case, it doesn't matter what the sensor resistance is, does it?

I checked the FSM last night and did the procedures and it seems that the sensor is good.  Its a single wire so I can't see how its shorted to ground.

There was a wire up by the battery in the harness that was just hanging there and had no terminal that I connected to ground (it was black).  Maybe that was it? 

The temp gauge is the only one that has an issue.  I pulled the cluster again and checked the traces and all that, which were gtg.

I know its something simple I'm missing.

Check the spade terminal with an Ohm meter for grounding, that
would be the easiest way. You can't chase down electrical problems
without a meter, or in the case of voltage issues, a lighted probe

Wild

I checked the FSM last night and did the procedures and it seems that the sensor is good.

Ok - now that you've gotten the FSM out, and you've followed the procedures to check the sensor, and it seems good, find the procedure to check the gauge, and follow that - if the gauge checks good, then the problem is most likely in the wiring.

Its a single wire so I can't see how its shorted to ground.

I can't see how you can't see it's possible for a single wire to be shorted to ground - the chassis is ground, so anywhere the single wire comes close to the chassis, it can be shorted.

Since we're looking at FSMs, I pulled mine and checked, the sensor has it's highest resistance when cold, and it's lowest when hot, so if that wire were actually shorted to the chassis, it would peg the gauge.

Ok, time to undo all the re-wrapping I did. Ugh. 

The gauge was good before I unplugged and messed with the wiring in the engine bay, so it's got to be a short.  The wire is most certainly not touching ground.  I bet its that stupid ground wire I connected up near the firewall/battery.  Didn't have a problem till I messed with that.

It could be unrelated, but its suspect.

Any insight why the dome light and indicators would flash when I turn off the ignition?  Doesn't happen when the ignition is turned on, just off. 

Incorrect grounds cause the strange happenings on these trucks