Excessively High Gauges

[86RangerXL]

Both my oil pressure gauge and my temp gauge have been really high.

My temp gauge read barely above cold for a while so I replaced the coolant temp sender, now it reads so high that it says its overheating even when the radiator and hoses are cool/cold so I've just been driving it and hoping that it's not overheating since I know the gauge is inaccurate. It seems to consistently stay at the line on the top of the "norm" section and sometimes moves up or down slightly, close but not going past the H though.

Now for my oil pressure gauge, it sometimes almost hits max, and usually stays concerningly high. It usually goes up on hills, but other times I'll be driving on a flat surface or even just coasting and the gauge will read almost maxed out. It goes both ways where sometimes it reads in the middle when going up hills.

I have no idea what's causing these considering both the temp sender and the oil pressure sender are brand new. My gas and ammeter gauge are perfectly fine though

 

[rusty ol ranger]

There is a voltage regulator behind the dash that controls those.

Its probably failed and is sending them full current.

No idea how to change it though.

I think @19Walt93 has described it before though

 

[19Walt93]

The constant voltage regulator in the dash is supposed to supply 5 1/2 pulsating volts, if it was causing the oil and temp gauges to be high, the gas gauge would be as well. It's not a big job to change: take the instrument bezel off, reach up behind the dash and pull the speedo cable- you'll feel a raised ridge on one side of the cable end, push on the ridge and pull down on the cable, remove the 4 screws holding the cluster in place and slide it back far enough to unplug the 2 wiring connectors. To get the bezel off you may have to reach behind the dash and push the spring loaded button on the headlight switch so the shaft and knob will pull out. The button is located just behind the mounting bracket.

 

[franklin2]

If you care about your truck, go buy some real gauges with real numbers. The cheap mechanical ones in the store are way more accurate and give you actual numbers. Then you can accurately monitor your engine.

 

[86RangerXL]

The constant voltage regulator in the dash is supposed to supply 5 1/2 pulsating volts, if it was causing the oil and temp gauges to be high, the gas gauge would be as well. It's not a big job to change: take the instrument bezel off, reach up behind the dash and pull the speedo cable- you'll feel a raised ridge on one side of the cable end, push on the ridge and pull down on the cable, remove the 4 screws holding the cluster in place and slide it back far enough to unplug the 2 wiring connectors. To get the bezel off you may have to reach behind the dash and push the spring loaded button on the headlight switch so the shaft and knob will pull out. The button is located just behind the mounting bracket.

The IVR is brand new too, forgot to mention that. But I never tested what voltage is actually coming out of it though

 

[86RangerXL]

If you care about your truck, go buy some real gauges with real numbers. The cheap mechanical ones in the store are way more accurate and give you actual numbers. Then you can accurately monitor your engine.

Yeah I might just do that that, even if it is just to check how accurate the stock gauges are

 

[superj]

Maybe you have a bad connection at the senders?

 

[19Walt93]

Maybe you have a bad connection at the senders?

Or a poor engine ground, I should have thought of that earlier. That's one way the gas gauge could be accurate while the other 2 are high.

 

[franklin2]

Yeah I might just do that that, even if it is just to check how accurate the stock gauges are

How accurate can "NORMAL" be? I am known as the stock gauge hater on another forum. And Ford is still doing it on the new trucks. What is "NORMAL"? I was once told it was a cycle on a clothes washer?

 

[86RangerXL]

How accurate can "NORMAL" be? I am known as the stock gauge hater on another forum. And Ford is still doing it on the new trucks. What is "NORMAL"? I was once told it was a cycle on a clothes washer?

As long as the middle of norm is running at a normal temp, and past norm is actually overheating I'm fine with that.

 

[86RangerXL]

Or a poor engine ground, I should have thought of that earlier. That's one way the gas gauge could be accurate while the other 2 are high.

I never even thought of that, guessing that has something do to with my half-disintegrated negative battery terminal. Like I can't even tighten the terminal clamp bolt kind of disintegrated

 

[19Walt93]

A poor ground will increase resistance and resistance is what the sending units create to make the gauges work.

 

[86RangerXL]

I never even thought of that, guessing that has something do to with my half-disintegrated negative battery terminal. Like I can't even tighten the terminal clamp bolt kind of disintegrated

Replacing the ground terminal changed nothing

 

[superj]

Check the other grounds too.

 

[rusty ol ranger]

There should be a ground strap attached from the firewall to the engine. On a 2.9 its bolted to the drivers side head in the back. If you have a 4 cylinder i dont know. But thats the ground for cab electronics.

Also since you have an 86 your gauges actually do "read" to a point. They are still unfourtantly dependent on voltage though.

It wasnt till mid year 87 they switched to the gauges that are idiot lights with a needle