Electrical - Need Help, Guage Fuse keeps Blowing

[Wallytoe]

Hello Toyota Van community, I have posted before on separate issues but didn't get any bites so I have been trying as much as possible not to fill up the forum with my questions but I am at a loss for ideas on this.

I have an 1984 Toyota Van LE 2WD
I have been studying the wiring diagram for the 87' because that is all I was able to find available online.

Since I purchased the Van the Illumination never worked.

However recently my Temperature Gauge, Tachometer, Oil Pressure Gauge, and Fuel Gauge all stopped working at the same time. I checked the GAUGE fuse and it was blown, so I a new one in and it didn't fix anything, the new fuse blew immediately. In the mean time I have been driving around without much time to work on it.

Today I removed the dash and am in the process of looking for the problem. I know nothing about electrical but I am beginning to understand a bit on the basics. I purchased a multimeter.

As far as troubleshooting and diagnosing the issue where should I start first?

In previous threads I read something about checking all the ground points first.

Also the digital clock also stopped working right before the gauge fuse blew.

[Burntboot]

Hey Wally - Sorry to hear your having so much trouble.
I suspect the reason your not getting any "bites" is do to the language you are using makes understanding the issue more difficult.

When you say "Since I purchased the Van the Illumination never worked" what exactly do you mean?
I might be tempted to assume you mean that the background lighting for the instrument pack was not functioning, but that would be a guess at best.
I imagine when you say that you removed the dashboard you really mean that you have removed the instrument cluster?

I wouldn't rely on the wrong manual for electrical, that is just asking for trouble.
Visual inspections always have their place but electrical problems are rarely solved that way.
What I mean to say is taking things apart to "look" for the problem isn't usually a productive process.
You will need to trace the circuit and assess potential problems.
You will need to be able to test the various switches and components as well as verifying there are no shorts within the harness.
You have to know what wires should be powered, which should be grounds, which ones switch.....
Its also important to remember the little things like what happens if you put power to the wrong wire and accidentally fry the ECU.
Not saying thats gonna happen, but it can and does.

You also have to figure out if the original problem has gotten worse or if you actually have 2 separate problems occurring
(my money would be on option #2, fwiw)

As far as WAG's go, I would probably start with the dimmer switch (it is turned on, right?) and work my way out from there.
Getting a hold of the proper wiring diagram will be of paramount importance, maybe someone else will be able to provide a pic of the pages you require?

BB

[Wallytoe]

Thanks for the response Burntboot, I appreciate the feedback on using appropriate and correct terminology.

The lights that light up the background for the instrument cluster haven't functioned at all. To get a better view of the wiring harness I removed the instrument cluster, radio, heater switches. I appreciate helping me think through the process. I will start my search for an 84' Wiring diagram, if anyone has a pdf file of this handy please send it my way!

What do you mean when you say WAG?

[Burntboot]

WAG = Wild Ass Guess
Not the preferred route but sometimes you have to start somewhere but guesses are usually the most expensive repair

The problem with dismantling to look is that often times you will disturb something, everything tests correctly, reassemble and fault still present
Broken wires have a really bad habit of remaking a connection temporarily when yanked about.
This repair method usually results in this action

Components have more moving parts than wires and are therefore immediately more suspect and should be tested for function first.
All ground points are ultra critical and must be inspected, anything that isn't clean and shiny is potential problem and MUST be addressed.

Lastly and possibly of most importance, this thing isn't wired like your old Chevelle.
If you ever heard someone say "I have power to everything but no ground", then proceeds to repair by making new ground connections, DO NOT let them anywhere NEAR your vehicle.

The General did things the old fashioned way, flip a switch to connect the power and go.
The Japanese realized that while this can be cheap, easy and effective it also results in more thermal events and that better function is attained by putting the switch on the NEGATIVE side of the circuit.
So, when you flip a switch you are connecting to GROUND!


It is the switch that controls what, where and when a ground connection will occur and just to make things even more interesting, sometimes a wire that is ground might even become a power wire, depending on how the switch is set up (fog and corner lights come to mind)

The wiring is less likely to be at fault and should be considered the last point of interrogation (barring obvious signs of failure - melted/discoloured/stiff)
(The exception would be connectors in the harness, they should all be inspected and cleaned)

BB