Ground problem maybe?

3488 Views 32 Replies 7 Participants Last post by cavalierhome, May 24, 2022

cavalierhome

Discussion Starter · Apr 23, 2022 (Edited)

I am trying to restore a 1986 samurai.
Everything was working fine, now, when I turn on the ignition the gas gage goes to ULTRA full the left directional ONLY blinks extra fast (the right one works fine) and the Tachometer reads 1,000 and when I rev the engine it maybe gets to 2,000 no matter how high I rev. If I leave the left blinker on for a while it stops all together and I have to shut off the ignition and wait a wile for it to start blinking extra fast again.

I have checked the ground at the left turn signal lamps it's good and the bulbs are good.

I have checked everything I can think of, I have changed the ignition switch and the entire turn signal horn etc setup.
I have run a thick ground wire from the battery very long so I can go to any ground (say the left signal) and ground it to make sure I have a good ground.

I can't find this and I have lost 2 days.

Any Ideas ? Any help much apricated.

Cheers

1 - 20 of 33 Posts

fordem

· #2 · Apr 23, 2022

Go to Ack's FAQ and find the wiring diagrams for the vehicle, you appear to have multiple issues.

Turn signals - assuming you haven't tried to fit LED lamps as a part of your restoration, the turn signal system uses a rapid flash rate to alert you to a failed bulb, so start by leaving the engine idling with the left turn signal on and walk around the car to see which light is out, and if they're all working, verify that the correct bulb has been fitted.

Gas gauge - the gas gauge is grounded via the sender in the fuel tank - check to make sure there isn't a short circuit somewhere behind there.

The tachometer is most likely an internal fault in the instrument itself - it gets a pulse signal from the ignition and reports what it sees

cavalierhome

Discussion Starter · #3 · Apr 23, 2022

Thanks, strange they all stopped working at the same time?
Everything was working fine.
I have no LED bulbs and the left turn bulbs are all good, but it all blinks extra fast.

cavalierhome

Discussion Starter · #4 · Apr 23, 2022 (Edited)

I don't know if this is important but when I run the engine and put on the directional signals (either side) the tachometer blinks with them, meaning that it jumps from 0 to 500RMM and back in sync with the blinkers.

Somehow this is all connected.

Any ideas?

Cheers

ButchW

· #5 · Apr 23, 2022

A short between systems in the instrument cluster?
Butch

cavalierhome

Discussion Starter · #6 · Apr 23, 2022

ButchW said:
A short between systems in the instrument cluster?
Butch

How would I find that there are millions of inches of wire under there?

ButchW

· #7 · Apr 23, 2022

cavalierhome said:
How would I find that there are millions of inches of wire under there?

Beats me... I'm pretty new to the Samurai club, and so far, haven't had any electrical gremlins... I do know that shorts can be can cause all sorts of weird behavior... Good luck..
Butch

cavalierhome

Discussion Starter · #8 · Apr 23, 2022

ButchW said:
Beats me... I'm pretty new to the Samurai club, and so far, haven't had any electrical gremlins... I do know that shorts can be can cause all sorts of weird behavior... Good luck..
Butch

Thanks. I am new too.

cavalierhome

Discussion Starter · #9 · Apr 23, 2022

Also does the 86 samurai have an ECU unit? I see a box behind the glove box? What is that? I have a wire schematic but it is not listed?
Tks
Cheers

fordem

· #10 · Apr 23, 2022

An 86 Samurai in the US would have left the factory fitted with an "electronic feedback" Hitachi carburetor, it does have an ECU of sorts, but it's not the same as you would have on a fuel injected vehicle. The Hitachi carbs have been quite problematic and many of them have been replaced with Webers, CV carbs from Harley Davidson motor cycles, and in some cases carbs from Toyotas.

fordem

· #11 · Apr 23, 2022

cavalierhome said:
I have no LED bulbs and the left turn bulbs are all good, but it all blinks extra fast.

I just want to point out one thing - all the bulbs can be good, and yet one of them does not light because of a bad ground or a broken wire - the flasher can't tell the difference - that's why I suggested you might want to walk around the vehicle and see if they all light.

cavalierhome said:
How would I find that there are millions of inches of wire under there?

Get under the dash and inspect the million inches of wires inch by inch or pay someone else to do it - you either have the test equipment and the knowledge/experience to perform electrical troubleshooting or you don't - we can only point you in the general direction to start a search. You have to know what your skills, resources & limitations are and act accordingly.

Turn signals are fed from their own fuse so they have a different power source to the tach and the fuel gauge, the dash turn signal indicators share a ground with the remainder of the dash, but the individual turn signals do not, the fact that one side works and the other doesn't suggests that the problem is related to the lamps or wiring on the affected side - this is unlikely to be related to either the tach or the fuel gauge issue.

The tach & the fuel gauge are powered from the ignition so they share a power source, the tach uses the dash ground, the fuel gauge does not, it's grounded via the sender in the tank - the only way to get the fuel gauge to register a full tank when it's not actually full is a short to ground on the connection between the gauge & the sensor - that short circuit can be physically anywhere between the gauge and the sender - that could literally involve an "inch by inch" examination of the wiring harness, or you could get lucky and as soon as you start searching you find a section of wire burned, pinched or even chewed (by rodents).

The tach, as far as I know, has three connections - power, ground and the ignition signal - the added information that the tach signal "bounces" with the turn signal suggests that there MAY be a ground issue with the dash cluster, but this is unlikely to be the cause of the fuel gauge issue or to cause one side of the indicators to malfunction whilst still allowing the other to work correctly.

As I mentioned earlier, you appear to have multiple problems.

See less See more

Reactions: 1

cavalierhome

Discussion Starter · #12 · Apr 23, 2022

fordem said:
I just want to point out one thing - all the bulbs can be good, and yet one of them does not light because of a bad ground or a broken wire - the flasher can't tell the difference - that's why I suggested you might want to walk around the vehicle and see if they all light.

Get under the dash and inspect the million inches of wires inch by inch or pay someone else to do it - you either have the test equipment and the knowledge/experience to perform electrical troubleshooting or you don't - we can only point you in the general direction to start a search. You have to know what your skills, resources & limitations are and act accordingly.

Turn signals are fed from their own fuse so they have a different power source to the tach and the fuel gauge, the dash turn signal indicators share a ground with the remainder of the dash, but the individual turn signals do not, the fact that one side works and the other doesn't suggests that the problem is related to the lamps or wiring on the affected side - this is unlikely to be related to either the tach or the fuel gauge issue.

The tach & the fuel gauge are powered from the ignition so they share a power source, the tach uses the dash ground, the fuel gauge does not, it's grounded via the sender in the tank - the only way to get the fuel gauge to register a full tank when it's not actually full is a short to ground on the connection between the gauge & the sensor - that short circuit can be physically anywhere between the gauge and the sender - that could literally involve an "inch by inch" examination of the wiring harness, or you could get lucky and as soon as you start searching you find a section of wire burned, pinched or even chewed (by rodents).

The tach, as far as I know, has three connections - power, ground and the ignition signal - the added information that the tach signal "bounces" with the turn signal suggests that there MAY be a ground issue with the dash cluster, but this is unlikely to be the cause of the fuel gauge issue or to cause one side of the indicators to malfunction whilst still allowing the other to work correctly.

As I mentioned earlier, you appear to have multiple problems.

So all the bulbs light up perfectly they just blink fast on the left side.

I will trace the gas gage to the cluster, cut the wire near the cluster and hook it up to a new gas gage sending unit. This way I can isolate all the wiring. If the problem resolves then I know I have individual problems or if the problem persists with the new unit then I know I have related problems elsewhere.

I will post results when I get the parts, unless I find some other solution while I wait for the delivery.

Cheers

2013GV

· #13 · Apr 24, 2022

Its sounding like a short or grounding issue, check for rodent damage in the loom, as Fordem says, the gauge is separate to the rest, but it all commons up in the loom under the dash. Mouse teeth, bare wire and a bit of earthed metal is never a good combination

cavalierhome

Discussion Starter · #14 · Apr 24, 2022

Some more weird things.
I disconnected the left rear light housing all together, signal, breaks, backup light etc. Fully expecting the fast blinking to continue or intensify.

Not only does it not blink at all on that side but more important the tach stopes working when I do.

Somehow this is all part of some other bigger problem.

cavalierhome

Discussion Starter · #15 · Apr 24, 2022

Ok solved the blinking problem but not the other ones. The blinking problem can be explained in one word. India. I purchased new lights all around for the car, and the lights came with bulbs. Because Fordem had made reference to the bulbs I went ahead and change the bulbs to the old ones that came with the car. Problem solved.

Now I am left with the tachometer. It continues to change speed with the blinkers. Any ideas on what that might be?

As for the gas gage I have a new sending unit on order let's see if that helps that.

I could really use some ideas on the Tach because I would love to button up the dash so I can begin to put the seats back in etc.

Cheers

fordem

· #16 · Apr 24, 2022

cavalierhome said:
Ok solved the blinking problem but not the other ones. The blinking problem can be explained in one word. India. I purchased new lights all around for the car, and the lights came with bulbs. Because Fordem had made reference to the bulbs I went ahead and change the bulbs to the old ones that came with the car. Problem solved.

That's actually there in my first response - verify that the correct bulb has been fitted - a lower wattage bulb draws less current, and that reduced current is how the flasher determines a failed bulb.

Now I am left with the tachometer. It continues to change speed with the blinkers. Any ideas on what that might be?

My suspicion is a loose or defective ground, either on the cluster itself or under the dash...

Schematic Font Slope Parallel Engineering

Pull the cluster out, eyeball the printed circuit on the back for signs of burning/damage, find the earth connection - it's in the upper left corner of the diagram - you'll need to match that to the physical connector - try adding a new wire from there to a clean chassis ground.

See less See more

Reactions: 1

cavalierhome

Discussion Starter · #17 · Apr 24, 2022

Will do.
Tks

ButchW

· #18 · Apr 24, 2022

fordem said:
My suspicion is a loose or defective ground, either on the cluster itself or under the dash...

View attachment 105800

Pull the cluster out, eyeball the printed circuit on the back for signs of burning/damage, find the earth connection - it's in the upper left corner of the diagram - you'll need to match that to the physical connector - try adding a new wire from there to a clean chassis ground.

With not knowing much about Samurais, this is what I would have checked 1st of all..
Butch

cavalierhome

Discussion Starter · #19 · Apr 24, 2022

The problem is that is was all WORKING before. so something fundamental changed and now it is bringing forward the weakest things.

I have to check the alternator to see if I am getting decent juice. it does run the car without the batery connected so it is working but maybe not enough juice.

And there is probably some ground issue although I have a manual ground I can est anywhere in the car and so far I have not been able to affect a change.

As I said it was all working perfectly before.

aquanaut20

· #20 · Apr 24, 2022

NEVER EVER run the engine with battery disconnected on a vehicle that has computers, may cost you dearly.

The battery is important to moderate spikes which are deadly for electronics

1 - 20 of 33 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.