Screwy readings on ALL guages
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Joined: May 2012
Posts: 208
Likes: 16
From: Kansas City MO
Car: 1987 IROC-Z convertible
Engine: 5.0
Transmission: 700R
Axle/Gears: 2:77
Screwy readings on ALL guages
I bought a 1987 IROC, 305/T5. It sat for 10 years under a big redwood tree. Just to get it started I had to tear out the entire dash and chase down quite a few gremlins. Here's where I'm at.
Not sure if this is related but before I tore the dash and the carpet out the power windows and power seat worked (not good but they worked).
My tach pegs out at max instantly and stays there. Fuel gage reads empty although I know the tank is completely full. Temp instantly reads 180 degrees even when engine is ice cold, No reading at all on the Alt gauge or oil pressure gauge. I can see that there is power to the cluster because some of the gauges do move when key is turned on. But as noted the Alt and Oil and fuel gauge dont move at all and others are obviously wrong.
I can say that there was a lot of corrosion on many of the pin outs and connectors through out the car, which I cleaned up. I'm fairy certain but not 100% certain that I cleaned all the grounds too. The printed circuit board on the back of the cluster looks pretty crappy too. There is also a little yellow electronic gadget screwed to the back of the tach side of the cluster and a wire runs over to the speedo side. What is that and is that a possible suspect? What would cause the windows and seat to stop working?
Thank You
Not sure if this is related but before I tore the dash and the carpet out the power windows and power seat worked (not good but they worked).
My tach pegs out at max instantly and stays there. Fuel gage reads empty although I know the tank is completely full. Temp instantly reads 180 degrees even when engine is ice cold, No reading at all on the Alt gauge or oil pressure gauge. I can see that there is power to the cluster because some of the gauges do move when key is turned on. But as noted the Alt and Oil and fuel gauge dont move at all and others are obviously wrong.
I can say that there was a lot of corrosion on many of the pin outs and connectors through out the car, which I cleaned up. I'm fairy certain but not 100% certain that I cleaned all the grounds too. The printed circuit board on the back of the cluster looks pretty crappy too. There is also a little yellow electronic gadget screwed to the back of the tach side of the cluster and a wire runs over to the speedo side. What is that and is that a possible suspect? What would cause the windows and seat to stop working?
Thank You
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Joined: Jan 2006
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Gage Rage
Your problem is consistent with an open ground even tho you think you have taken care of those.
So let’s fix one gage and it might rectify other problems.
Fuel Gage:
Remove the sender wire going to the gage.
Tape the bare end of the sender wire and put it aside.
Use a potentiometer with a value of 100Ω or the closest you can find.
Connect one end the potentiometer to the gage from the location you removed the sender.
Connect the wiper of the potentiometer to ground.
Turn the key to RUN.
Slowly adjust the potentiometer from 0Ω to 90Ω.
If the gage is bad it will exhibit the problem you have.
If the gage is good it will display a smooth transition from one end of it’s range to the other.
Therefore the problem is with the sender, wiring going to it, or open ground.
You can use a loose potentiometer, or you can throw together a quick little panel like this one.
Both systems failing simultaneously is consistent with a blown Fusible Link.
Fusible Links usually look like a one inch plastic rod in line with the wire and are located near the battery or at the starter.
Use a voltmeter or wired bulb to probe both sides of the Links.
You need to have power on both sides referenced to ground.
Keep the engine off when testing.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing !
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If We Don’t Get Cawt We Ain’t Cheatin’
So let’s fix one gage and it might rectify other problems.
Fuel Gage:
Remove the sender wire going to the gage.
Tape the bare end of the sender wire and put it aside.
Use a potentiometer with a value of 100Ω or the closest you can find.
Connect one end the potentiometer to the gage from the location you removed the sender.
Connect the wiper of the potentiometer to ground.
Turn the key to RUN.
Slowly adjust the potentiometer from 0Ω to 90Ω.
If the gage is bad it will exhibit the problem you have.
If the gage is good it will display a smooth transition from one end of it’s range to the other.
Therefore the problem is with the sender, wiring going to it, or open ground.
You can use a loose potentiometer, or you can throw together a quick little panel like this one.
Originally Posted by neilcase
What would cause the windows and seat to stop working?
Both systems failing simultaneously is consistent with a blown Fusible Link.
Fusible Links usually look like a one inch plastic rod in line with the wire and are located near the battery or at the starter.
Use a voltmeter or wired bulb to probe both sides of the Links.
You need to have power on both sides referenced to ground.
Keep the engine off when testing.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing !
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
If We Don’t Get Cawt We Ain’t Cheatin’
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