View Full Version : different electrical problems

07-29-2006, 09:14 PM
So my sister was driving the 40 this week and called me telling me that the fuel gauge and engine temperature gauge weren't working. I'm like great :rolleyes:

Only things I can think of are 1) it rained the night she drove it and it got a little wet. However this truck has gotten REALLY wet on the inside before with no problems. Also now that it's been dry for a couple days I would think they would work but they don't. 2) I washed the inside of the truck after the Ghost Town run, but kept it just to the tub. The fuel sending unit might have gotten wet, so maybe that's causing a problem.

I noticed this evening when I started the truck when it was cold the fuel gauge went up but then got shaky and went back to dead mode. Don't know what this means. All the fuses are good, anyway if the fuse for the instruments was dead my oil pressure gauge wouldn't work either, and it does. Help please? :D

Shark Bait
07-29-2006, 09:20 PM

If the fuel gauge is like the oil pressure gauge, you can test it by grounding the wire that connects to the sender. The gauge should peg all the way to F. That's about all I know, though. Is the ground wire still connected? I HATE electrical problems! If you want that harness, I've started hacking in to it, but you can sure have it back to use/look at.

07-29-2006, 09:27 PM
Any chance the back of the gages are just corroded a little? Are these anything like 62's? On those you'll be driving along then all of a sudden the temp will just peg, or the pressure wigs out, etc. So you pull the dash then clean up the contacts & so forth.

Remember that cruizers.com board like 3 years ago? That's where I learned that.. when I had a 62. Man that was a while ago, before you were Subzali even.... :) then everyone migrated over to Mud...

Anyway I hope that helps, sorry I've never been in a 40 dash. Still a pup I guess. :o

07-30-2006, 12:09 AM
Well it looks like I'm an electrical wizard :rolleyes:

Both gauges work fine now, maybe they got wet and they just had to get cycled a couple times/used a little bit to get them to work again. I don't know, I just wish the same kind of thing would happen for my turn signals.

Yeah that cruizers.com board was WAY before I had the Cruiser...there's still some people like Yoshiman that still frequent that place...can't figure out why though. All I ever go to that website anymore for is the classified section, it's still pretty good.

07-30-2006, 12:25 AM
Wait.... you have a sister that drives a Land Cruiser? :D

07-30-2006, 09:11 AM
...I just wish the same kind of thing would happen for my turn signals...

What are your turn signals doing? I recently had to rewire turn signals on my 73 FJ40. They were doing all sorts of strange things. When the headlights were on, the front didn't work, back only worked on the passenger side. With headlights off they all worked, but weak on the driver side and nothing in the back with brake lights on, etc... It ended up being a combination of bad grounds all around, an after-market flasher under the dash, and a poorly spliced in trailer harness in back. I pulled all the unnecessary wires in back, cleaned up all the grounds and replaced the bullet connectors, added a correct Toyota flasher unit and it works perfect now.

My horn also wasn't working and that ended up being rusty/dusty connections inside the steering wheel where the buttons contact. I imagine that the connections for the gauges are probably in similar condition behind the dash which causes them to function sporadically.

07-30-2006, 10:44 PM
then everyone migrated over to Mud... Not me, I'm a die hard Lister.

07-30-2006, 10:58 PM
Matt, on your 77 the gauge connections will be through a circular multipin connector on the back of the cluster. It is in a protected place and seldom corrodes or even gets very dirty. Since you had two gauges acting flaky at once it is unlikely to be a sender, a bad ground, corrosion, or the result of your washing the inside.

The connector is soldered to a circuit board that extends across the back of the cluster and it is possible that through years and vibration you have one or more intermittent solder joints there, likely on a trace that provides power to both gauges, since the senders provide a resistive path through the gauges to ground. Since the problem seems to have corrected itself for the time being, I wouldn't worry about it unless it reoccurs, at which point you should pull the cluster and examine those solder joints under strong lighting and magnification.

If it's not a solder joint, it could also be one of the female terminals in the connector that has simply gotten loose and lost it's tension on the male pin. Again, it would be one of the ones (there are several, but only one for the temp and fuel) which provide power to the gauges. HTH and happy cruisin'!

07-31-2006, 06:16 PM
well they stopped working again, and then worked again, but now seemed to have stopped for good, as now tapping on the gauge glass doesn't make them work anymore :( That's okay I was planning on taking it apart and looking at it anyway. I guess the ghost town run just did it in...

Hey Jeff you're having a Cruiser electrical discussion at the meeting this week right? ;) BTW is anybody meeting to eat prior to the meeting?

08-13-2009, 01:59 PM
This problem is still ongoing (though I had forgotten I had posted about it). It seems to get worse if I've been doing a lot of 4-wheeling (don't know if it's the bouncing or the dust). I'm getting closer because I have an FSM and there is a good page about how to test these circuits - sometime I will have to dig into that deeper and see what I can find out.

08-13-2009, 02:50 PM
Same thing is going on with my 77, I'm gonna keep a close eye on this thread. goofy Blinker stuff going on and every once in a while the guages no workie...then! magically! they start working again. Exactly as you've posted.

Once I get this VW sold, there will be more attention to the 40.

08-13-2009, 03:05 PM
you're selling the Ghia!?

There is common power for the oil, fuel and temp. oil gauges. My oil gauge doesn't have problems so I'm thinking there is a problem after the oil gauge splits off. I have tried two different instrument cluster back panels with no change in the result, so Zepp's idea was a good one but not applicable to my case unfortunately :(

08-13-2009, 07:29 PM
Wow! A revived thread from 2006 :eek:

Now here's a cliche':

Check your grounds :lmao:

Seriously, if it is somehow related to vibration/bumpy wheeling, it must be electro-mechanical.

Troubleshooting by swapping out clusters was awesome. That eliminates the cluster!

Visual examination of connectors is a great technique and verifies faults much, if not most of the time on these older rigs. Wiggling while the symptom is present is often help too. Wiring itself is seldom but occasionally the cause, but I would check connections first before replacing the loom wires.

08-13-2009, 08:28 PM
Well Jeff you're right in my case it's probably a connection somewhere near the instrument cluster, but not the cluster back panel itself.

These two circuits ground individually through their respective sending units, so having both of them lose power for grounding problems at the same time is not likely, impossible really. So it's a problem with the power supply.

And thank you for mentioning wiggling - most of the time if I tap the instrument cluster glass they will power back up. But when it gets really bad they won't. Like last year in Moab, when I 4-wheeled 10 days in a row. They didn't like that and I didn't know my engine temp. or fuel the whole way home :eek: But some time later they came back and are with me now. BUT the point of this is that I know the problem is somewhere near the cluster, some kind of connection, but I just don't know exactly where. I just have to start tracing wires...

08-14-2009, 06:44 AM
damn those electrical gremlins... the chase continues.

And yup...selling the Ghia. It's a tough decision for sure. :(
However...there is a good reason. Kiddo #2 is on the way and due Ocotber.:thumb::thumb: (yikes! Note to self, "Self. enjoy the sleep now) Any-hoo...that's the good part.:D So basically, I need the dough (kneed the dough?? :D :lmao:)

08-14-2009, 11:05 AM
This may not be the whole solution, but as part of it...

I've seen the fuse clips in the fuse panel get just a bit rusty, causing all sorts of erratic electrical problems. You can remove the glass fuse, disconnect the battery, and put a .22 cal. gun cleaning brush (brass) in a drill, and spin the brush in the fuse cavity. It will clean those up in a hurry. My headlight fuse was hot to the touch when the headlights were on, due to excessive fusebox clip resistance. (Yeah, I know - the real solution is to rewire the headlights with a relay..)

Anyway, cleaning up all fusebox clips is never a bad idea on an older truck.

08-14-2009, 12:12 PM
However...there is a good reason. Kiddo #2 is on the way and due Ocotber.:thumb::thumb: (yikes! Note to self, "Self. enjoy the sleep now) Any-hoo...that's the good part.:D

Congrats to the Cardinal family :thumb:

08-14-2009, 12:14 PM
Thanks Steve, yes when I first bought the truck all the fuse clips needed cleaning. They are probably due for another.

I think I will do that plus I will check into the instrument cluster connectors and such, seeing as tapping on the glass made the gauges come back to the land of the living more often than not.

12-06-2009, 02:55 PM
I'm guessing the temp. sending unit should be receiving a constant 12V right? The oil pressure sending unit does...and the gauge value is based on the resistance - effectively the gauge measures the amps?

My temp. sending unit is getting erratic voltage readings, which I'm guessing is the reason why my temp. gauge isn't really showing me much...now I have to find out why that connection is broken upstream of the sending unit...sigh.

12-06-2009, 03:35 PM
My temp. sending unit is getting erratic voltage readings, which I'm guessing is the reason why my temp. gauge isn't really showing me much...now I have to find out why that connection is broken upstream of the sending unit...sigh.

I don't know what voltage it should be getting, but it was my understanding that the fuel, temp and oil pressure gauges reflect resistance. My temperature gauge was working erratically, turned out that the plug that goes onto the temperature sender was working loose from the wire. Didn't really figure it out until the full physical separation occurred with the parts in my hand:p:. I spliced on a new flat female spade connector - it was a bit narrow but with some gentle modification is is snuggly in place and working great.:thumb:

12-06-2009, 04:54 PM

12-06-2009, 06:54 PM
Sorry, don't see anything?