Ke70 dash wiring

[Jentriken]

Hi, I have an ‘82 ke70 and most of the cluster doesn’t work and idk why, the Speedo works( obviously cos that’s mechanical) but the clock, fuel gauge and the fuel light don't. The temp also doesn’t work but that doesn’t bother me as I have an aftermarket water temp. not sure if other lights work except the indicators and high beam lights work?. I’ve tried 3 different fuel level senders, checked the plugs at the back of the dash, checked fuses and nothing has changed. Where do I go from here? Does anyone have a decent diagram or even list of all the main wires behind the dash?

[altezzaclub]

There's no wires, they are all on a sheet of plastic...  I kid you not!

I assume you have seen it when you checked the 3 plugs at the back. If you want to pull it all out the instructions are in this topic about changing auto to manual gearboxes from years ago-

https://www.rollaclub.com/board/topic/58879-how-to-convert-an-auto-to-a-manual-ke70/

and a wiring diagram is here-

https://www.dropbox.com/s/s0xs2udvrv9qfl2/downloadfile.jpg?dl=0

Red/Green supply the clock, yellow/red and yellow/green the fuel gauge and temperature.

See how you go, it might be a bad earth, or separate problems, or a need for a review of all the wiring.

 

 

 

 

 

 

 

 

 

[Banjo]

Hi Jesse,

                I looked up a previous post of yours back in July, & I believe this 1982 KE70 with a 4K engine, is one that you indicated it had some "dodgy" wiring, which was the result of a previous owner.

One of the problems with the "plastic" coated thin copper flat "printed circuit type" wiring on the back of the dash, is that it is extremely thin, & can burn out, & go open circuit.  There is a fuse on your fuse box called "Guages", & this feeds 12 volt power to eight (8) items . . . . .

 

No: 35  Braking Warning Lamp.

No; 47  Low Fuel Warning Lamp.

No: 59  Rear Licence Plate Lamp.

No: 60  Parking Brake Warning Lamp.

In addition, there are four (4) guages.

No: 109  Oil Pressure Guage.

No:   13   Fuel Guage.

No: 185   Tachometer.

No: 194   Water Temp Guage

If any of these are working, then it indicates the 10A "guage fuse" is OK.  However, I would check that it is actually a 10A fuse, & hasn't been substitued with a 15A, or 20A, fuse.

If any of these items are working, then the non working items, will have an open circuit in the grounding side, which could be a switch, or an earth/ground track on the printed circuit plastic wiring. Only careful inspection visually, with a magnifying glass; or checking continuity with an "ohms" range, a multimeter, is going to determine where this fault lies. 

Let us know how You go.  Just tackle it one item at a time, & when you find the fault, it may correct more than one item, that is not working.  Bear in mind, that as this car has dodgy wiring, there may be more than one fault, you will have to find.  Just start with say the rear licence plate, as that is the most likely place a short circuit, that could create an open ciruit, & stop other items from working, if it has burnt out the copper track on the back of the dash instrument cluster, which is a common circuit to more than one of the above listed 8 off items.

Cheers Banjo.  

Edited August 15, 2023 by Banjo

[Jentriken]

1 hour ago, Banjo said:

Hi Jesse,

                I looked up a previous post of yours back in July, & I believe this 1982 KE70 with a 4K engine, is one that you indicated it had some "dodgy" wiring, which was the result of a previous owner.

One of the problems with the "plastic" coated thin copper flat "printed circuit type" wiring on the back of the dash, is that it is extremely thin, & can burn out, & go open circuit.  There is a fuse on your fuse box called "Guages", & this feeds 12 volt power to eight (8) items . . . . .

 

No: 35  Braking Warning Lamp.

No; 47  Low Fuel Warning Lamp.

No: 59  Rear Licence Plate Lamp.

No: 60  Parking Brake Warning Lamp.

In addition, there are four (4) guages.

No: 109  Oil Pressure Guage.

No:   13   Fuel Guage.

No: 185   Tachometer.

No: 194   Water Temp Guage

If any of these are working, then it indicates the 10A "guage fuse" is OK.  However, I would check that it is actually a 10A fuse, & hasn't been substitued with a 15A, or 20A, fuse.

If any of these items are working, then the non working items, will have an open circuit in the grounding side, which could be a switch, or an earth/ground track on the printed circuit plastic wiring. Only careful inspection visually, with a magnifying glass; or checking continuity with an "ohms" range, a multimeter, is going to determine where this fault lies. 

Let us know how You go.  Just tackle it one item at a time, & when you find the fault, it may correct more than one item, that is not working.  Bear in mind, that as this car has dodgy wiring, there may be more than one fault, you will have to find.  Just start with say the rear licence plate, as that is the most likely place a short circuit, that could create an open ciruit, & stop other items from working, if it has burnt out the copper track on the back of the dash instrument cluster, which is a common circuit to more than one of the above listed 8 off items.

Cheers Banjo.  

Yea ok, so I just checked, the license plate light and fuel level sender have power at the rear of the car and the gauge fuse is 10a and intact, I'm gonna start pulling apart the dash again, hope I find something 

[Banjo]

Hi Jesse,

                The fact that You have +12 Volts at both those points, indicates that "the issue" is on the ground/earth side of the connections.

Earlier model Corollas, pre your KE70; had a system where the power fed to the instruments like guages, was a DC voltage lower than 12 Volts.  Usually, it was 7, 8, or 9 volts, off memory.  The reason for this, was that the voltage in your car is never a constant 12 volts.  The lower voltage was to ensure, that irrespective of what the battery voltage was, the guage had a fixed/steady voltage, so that it always read accurately. I'm presuming, that the instrument guages used in the KE70, have a small voltage regulator built in to each guage. In the older model Corollas, when this regulator burnt out, all the guages just stopped.  However, your KE70 is wired differently. Before pull out the dash again, it would be a good idea to test the Park Brake, & Brake Warning lights. Both these switches just connect a ground or earth to their respective wires. The brake warning light, is probably a sensor in the brake master cylinder, to indicate when the fluid is getting low.  Earth connections, in places like under the floor, or in the engine bay; often go open circuit, or high resistance, because of corrosion.  Particularly, if the DC currents are very small, like milliamperes.  Give all these earth connections a good clean.

Cheers Banjo

 

Edited August 15, 2023 by Banjo

[Jentriken]

Ok so I’ve pulled the cluster and it seems to have continuity across the parts it should and it looks fine. I did find that the fuel gauge wire was cut and spliced into an 12v ON wire on the ignition. I’m assuming this was to send power to the electric fuel pump he had back there. I tried jumping the wire back to its original connection but still no gauge on the dash. Also it looks like there’s some aftermarket relay for something but I’m not sure what for, may be related?

[Banjo]

Hi Jesse,

               That relay you referring to, is not a relay.  Relays always have more than 2 wires to them.  That is a flasher unit.   It says so on the side.

If it is connected to anything related to guages & warning lights, I can image it is causing issues.  Maybe the previous owner was trying to make the "warning lights" blink.  Who knows !  It wouldn't work ! There is usually not enough current from "pilot" lamps to drive the "in-line" flasher. Remove it, join the red & white wires togetherm, & see whether that is the issue.

Forget about the fuel guage for the moment.  The sender unit provides a ground or earth connection, through a variable resistor.  Leave that till last. Once you got the rest working, I'll advise how to test the fuel guage.  Fuel level sensors in the tank, are notorious for "playing up".

Your best friend, in this kind of electrical fault finding scenario, is one of these.

Have you got one of these ?  This one is $6- $7 on ebay

Cheers Banjo

Edited August 15, 2023 by Banjo

[Jentriken]

1 hour ago, Banjo said:

Hi Jesse,

                The fact that You have +12 Volts at both those points, indicates that "the issue" is on the ground/earth side of the connections.

Earlier model Corollas, pre your KE70; had a system where the power fed to the instruments like guages, was a DC voltage lower than 12 Volts.  Usually, it was 7, 8, or 9 volts, off memory.  The reason for this, was that the voltage in your car is never a constant 12 volts.  The lower voltage was to ensure, that irrespective of what the battery voltage was, the guage had a fixed/steady voltage, so that it always read accurately. I'm presuming, that the instrument guages used in the KE70, have a small voltage regulator built in to each guage. In the older model Corollas, when this regulator burnt out, all the guages just stopped.  However, your KE70 is wired differently. Before pull out the dash again, it would be a good idea to test the Park Brake, & Brake Warning lights. Both these switches just connect a ground or earth to their respective wires. The brake warning light, is probably a sensor in the brake master cylinder, to indicate when the fluid is getting low.  Earth connections, in places like under the floor, or in the engine bay; often go open circuit, or high resistance, because of corrosion.  Particularly, if the DC currents are very small, like milliamperes.  Give all these earth connections a good clean.

Cheers Banjo

 

I can’t see any wires around either the brake master or the handbrake so not sure what to test but I did just remember the cut section of harness in the engine bay, do some of these need to be grounded to run the dash?

[Banjo]

Which part of the KE70 car floor, is your photo of ?

Cheers

[Jentriken]

52 minutes ago, Banjo said:

Hi Jesse,

               That relay you referring to, is not a relay.  Relays always have more than 2 wires to them.  That is a flasher unit.   It says so on the side.

If it is connected to anything related to guages & warning lights, I can image it is causing issues.  Maybe the previous owner was trying to make the "warning lights" blink.  Who knows !  It wouldn't work ! There is usually not enough current from "pilot" lamps to drive the "in-line" flasher. Remove it, join the red & white wires togetherm, & see whether that is the issue.

Forget about the fuel guage for the moment.  The sender unit provides a ground or earth connection, through a variable resistor.  Leave that till last. Once you got the rest working, I'll advise how to test the fuel guage.  Fuel level sensors in the tank, are notorious for "playing up".

Your best friend, in this kind of electrical fault finding scenario, is one of these.

Have you got one of these ?  This one is $6- $7 on ebay

Cheers Banjo

I tried connecting those two wires going to the flasher thing and nothing 

its actually 3 wires at a plug but not sure what it’s meant to do but one of the wires is 12v ignition and another is ground. Don’t reckon it’s connected to the gauges afterall

 I did find these two unplugged wires too tho

[Jentriken]

13 minutes ago, Banjo said:

Which part of the KE70 car floor, is your photo of ?

Cheers

Sorry it’s under the dash at the fuse panel behind the speaker cover thing

[Jentriken]

20 minutes ago, Jentriken said:

I tried connecting those two wires going to the flasher thing and nothing 

its actually 3 wires at a plug but not sure what it’s meant to do but one of the wires is 12v ignition and another is ground. Don’t reckon it’s connected to the gauges afterall

 I did find these two unplugged wires too tho

Nvm I figured that out it seems like to flasher is what’s contributing the indicators/hazarts

[Banjo]

 

Hi Jesse,

                Bear in mind that there is a colour code for all the wiring in your car, that can greatly assist, in tracing wires, when you are working blind, as You are, because You have no idea, what the previous owner did, which appears to be pretty drastic, in places.

 

For example, in your picture above You are holding two" red" wires.  One appears to have a "light blue" stripe; the other doesn't seem to have any colour stripe at all. 

If you look at the wiring diagram, at the area, of interest to you, which is the warning lamps & guages, you will notice that the power wire coming from the 10A fuse, to all guages & warning lights, is coloured Red with a Light Blue stripe.  This should have +12V on it, if the fuse is OK, & the ignition is on.

Just test every part of the circuit that way, with a test light, with the clip connected to a good earth. 

Take for example the Fuel Warning Lamp.  according to the wiring diagram, it should have +12V power fed to it by a red wire with a light blue strip.

The other side of this fuel warning lamp, should have a yellow wire with a light blue strip.

This of course assumes that when Toyota manufactured these cable looms, they had all the colour coded wires available.  I found to my horror years ago, when rewiring my KE30 Corolla, where a wire colour would change from one colour to another, from end to end. When I unwrapped the loom, I found a crimped join in the middle of the loom, where they ran out a particular colour, & substitued another colour.

You will only solve the horrible wiring mess You have inherited, by systematically working through this, circuit by circuit.

Hope this assists.

Cheers Banjo

 

Edited August 15, 2023 by Banjo