1972 FJ40 gauge issues (1 Viewer)

[R.K.]

I just finished refurbishing the instrument cluster in my ‘72 FJ40. Upon reassembly and reinstallation, I have noticed a couple of issues.

The fuel gauge reads backwards. I verified this by adding fuel. It also settles to right (F) side when the switch is off.

The temperature gauge also reads backwards when the engine warms up. It was settling to the right (H) side with switch off, but is now settles to the left (C) side with switch off.

The leads were reconnected to the same posts as they were before disassembly.

Any ideas?

 

[R.K.]

Here’s a pic of the instrument cluster after the rig was shut down and rested for a few minutes.

 

[charliemeyer007]

DC is directional - hooked up backwards can make things work backwards or release the magic smoke. Fuel gauge is powered @ like 7V from the ammeter.

Ign off - temp should read Cold, Gas should read Empty, Ammeter needle should be centered

 

[franklin40]

On my 72 with ign off my temp reads hot . once it’s started the needle drops to the left and then swings to hot again as it warms up it just doesn’t go all the way past hot marking like when the ign is off. From my reading while wiring the gauges this is the way its supposed to work on the early 72 gauges anyway

 

[charliemeyer007]

My gas gauge has never worked right - reads full for a very long time, 1/2 is more or less good and E - I'm walking. The reason why I added an aux tank. I installed a switch on the dash and carefully selected the proper amount of 2% resistors to get the gauge to read the Datsun B210 tank/sender to read E for empty and 1/2 which was full in the 12.5 gallon tank.

The oil pressure gauge always read low, even with a new sender. I installed a lighted direct read gauge on the steering column. I enclosed the nylon oil hose from the fitting on the gauge to the engine side of the firewall in rubber oil line - that way if the nylon hose ever failed I would not get a face full of hot oil.

 

[R.K.]

DC is directional - hooked up backwards can make things work backwards or release the magic smoke. Fuel gauge is powered @ like 7V from the ammeter.

Ign off - temp should read Cold, Gas should read Empty, Ammeter needle should be centered

How can the gauges be hooked up backwards? It saying they aren’t, would just like to verify if they are backwards.

 

[45Dougal]

Some gauges rest to the right with no power, but if you're filling the tank and the needle goes down then its more likely that you have the wrong sender fitted.

Temperature gauge maybe had a short circuit to ground? Check the sender wire

 

[charliemeyer007]

Oh I did check my temp gauge today, it does go past the H with no power. Looks like I'll be rebuilding the hazard switch.

 

[charliemeyer007]

Bench testing is more likely to result in hooked up backwards. Proper colored leads will help prevent that

I just checked my temp gauge does indeed go past H when off.

 

[R.K.]

Bench testing is more likely to result in hooked up backwards. Proper colored leads will help prevent that

I just checked my temp gauge does indeed go past H when off.

What exactly could be connected backwards? I took this pic before disassembly, and matched it during reassembly. Unless I swapped two gauges inadvertently before adding the faceplates to them.

 

[charliemeyer007]

It can happen when you take the gauge apart.

For example neighbor lady ask me to look at some electric lanterns after the second power outage in two weeks. The lead acid battery is shot in this one - cost more to buy some battery that can fit than it is to just get a new LED unit. Anyway none of the stuff inside is marked. I could get it to work but if it is unconnected for a while then it is a real PIA to get it working again.

 

[45Dougal]

What exactly could be connected backwards? I took this pic before disassembly, and matched it during reassembly. Unless I swapped two gauges inadvertently before adding the faceplates to them.

View attachment 3684127

That does sound like a real possibility if you took the face plates off

 

[R.K.]

I’m guessing I swapped some of the gauges when the faceplates were off by mistake. How does one distinguish between the oil pressure, coolant temp, and fuel level gauges?