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Gas gauge and signal light don't work


JDMClassic

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More info.

 

Did this just happen or have they always been this way?

 

Have you done anything lately to the electrical system. Have you removed the dash?

 

Turn signals on. Do they flash on the outside of the car? In other words do the turn signals work, just the lamp in the dash does not?

 

Gas and temp gauge are powered from the same fuse so... Does the temp gauge work?

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More info.

 

Did this just happen or have they always been this way?

 

Have you done anything lately to the electrical system. Have you removed the dash?

 

Turn signals on. Do they flash on the outside of the car? In other words do the turn signals work, just the lamp in the dash does not?

 

Gas and temp gauge are powered from the same fuse so... Does the temp gauge work?

I'm having a similar problem with my 620.

 

1) Problem has just started.

2) Yes, I've been trying to wire up the aftermarket head unit that the previous owner installed, its currently wired up so it only runs when the key is in the ON position, I want it on the accessory.

3) Indicators don't flash on the inside or outside.

4)Temp gauge doesn't work either

 

Thanks in advance for any help, much appreciated

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2/ Look on the ignition switch plug. The Blue wire is the accessory.  It is has power in the ON and ACCESSORY positions.

 

3/ Find the emergency four way and the turn signal flashers, they're under the dash near the steering column, little aluminum cans with two wires each. Something like this...

75-11977.jpg

If one is missing get another. If there are two, swap them and try the signals. If now working the flasher was bad, get a new one. If neither helps check the fuse box.... (everything upside down left is right) it will be the 10 amp fuse with the Blue/Black stripe wire coming from it.

 

4/ Temp gauge AND gas gauge not working could be the fuse but if the brake, oil pressure and charge lights work, not likely. Find the temp sender, usually on the thermostat housing. It has a Yellow/Black stripe wire to it. Pull off and ground it to the engine block and the temp gauge should read FULL HOT. If it does the sender is bad. If not, and the Gas and Temp gauges are not working together then it's likely the small voltage regulator that powers them both.The voltage regulator is located in the temp gauge and has a wire wound metallic strip and a set of contacts. Wire heats up, strip bends and opens contacts, strip cools, contact made, repeat. The points just need a fine strip of sand paper pulled gently through them to clean and good for another 40 years.

 

620instvoltreg.jpg

 

....and I'm spent.

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If the temp gauge works then there is power and the volt regulator for goth seems fine. What I would do is go to the gas tank, look on top and you'll find two wires to the sender.

 

Clean the dirt and rust away and make sure the wires are on and in good shape, clean and not loose.

 

Next check the plug for corrosion as the tank gets all kinds of rocks, dirt and spray.

 

Ground the Yellow wire with the key ON. Gauge should read FULL if the wiring is good forward to the dash. If it doesn't read, check the harness along the frame for ANY damage. There is a 10 pin connector inside the cab on the floor under the pass side seat. It may be loose or corroded from a wet carpet. Again, grounding the yellow wire will tell you if the under cab harness is good or not if the gauge begins to work.

 

If grounding the yellow wire works but not when connected to sender, then ground the black wire. If it begins working then this ground wire is damaged. Find a new ground connection somewhere under the truck and connect it to the black wire.

 

If none of this works the sender may be bad.

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