I have a 1964 mustang with a six cyl. all gauges dont work. put in a new oil pressure sending unit, has a new fuel tank with sending unit,new temp. sending unit wires are all hooked up. I need help finding the problem

power goes through the gauge down to the sender unit ,through the resistance to ground
what you have indicates a short in the wire after the gauge and before the sender unit

A vehicle that old will need all the wire connections cleaned and tightened. Also may need new oil pressure sending unit, and new temp sending unit. Might need new speedometer cable and fuel gauge sending unit in the gas tank.

Yes, the sending unit is in the tank. If you unplug the connector at the tank and ground the gauge's sender unit wire to metal, with key on, the dash gauge should jump to full or near full. This verifies the dash gauge is working properly, and the problem is with the sender unit in the tank. If the gauge doesn't move when grounded, then the gauge or wiring from tank to gauge is not correct.
Good luck.

if temp, does not work, it may be the tempurature sending unit. for fuel guage it is usually a bad wire to tank or the sending unit in tank. check wire and ground to tank first. good luck!!

Voltage from the battery goes through the ignition switch, through a device in the instrument cluster called a voltage regulator (though it is really misnamed), through the gauge, through the wiring to the gas tank, through the sending unit in the gas tank to ground.

The sending unit is an electrical wiper that slides across a peice of resistance wire. the movement of the float moves the wiper. If the sending unit no longer makes electrical continuity, the gauge will read zero. If the sending unit wiper is shorted out, the gauge will read full.

Try grounding the wire at the tank to see if the gauge maxes out, then disconnect it to see if the gauge zeros out. If all that happens, your problem is the sending unit in the tank. If none of that happens, your problem lies closer to the front of the car. While you are under there, you should measure the resistance from the terminal on the tank to ground, just to verify that the sending unit makes some electrical contact.

If the other gauges work OK (temp, oil pressure) then the "voltage regulator" is probably working fine, and the problem is the gauge itself.

If you have no other gauges (excluding speedometer, tachometer and battery voltage meter -- they work differently), then try this:

Put a voltmeter on the part of the fuel level gauge that is supplied by the "voltage regulator." The voltage there should regularly cycle between near zero to 10 or 12, back to near zero, etc. If you get that cycling, then it is most likely the gauge.

Hi, you will have to replace all sending units for these gauges in order to restore them to there original state. i will list the sending units and there respective locations below.

1. Fuel gauge sending unit- you will need to replace the fuel sending unit on your Olds. its located inside the actual fuel tank. there's a floater attached to this Assembly and , its broken. you will have to replace the entire assembly. you will also have to drop the fuel tank to access it as well.

2. Temp guage-- normally when this guage starts to malfunction, its because of a bad coolant temperature sensor. Inspect the sensor's wires and connections. ECT (engine coolant temperature) sensor problems are often caused by faulty wiring or loose or corroded connections rather than the failure of the sensor itself. If the wires or connections are bad, replace them. If you think the sensor is defective, it should be tested.

This sensor is located Under hood, center, upper engine area, front of carburetor, passenger side of water outlet, mounted in intake manifold.

3. Amp gauge --- OK, this can be caused by a bad voltage regulator. i would also trace every single wire from the amp gauge to the sensor and regulator. check for corroded connectors and contact clips. replace any wire that may seem worn.

4. Oil pressure gauge-- This gauge will malfunction if the Oil pressure switch is faulty or not working. This is an Information relay unit for the indicator light or gauge on instrument panel. It contains a diaphragm that responds to changes in oil pressure. When the oil level is over a pre-set limit, the diaphragm opens the switch, turning off the light. When level is below the pre-set limit, the dash light comes on. In later model cars, if the oil pressure drops, the switch turns off the fuel pump, to stop the engine and limit damage to internal parts. Oil pressure switches can be grouped into two categories, units for electrical gauges and for mechanical gauges. If this switch is defective, it will have to be replaced. Once replaced, it will fix the dead oil gauge.

This device is located Under the hood, passenger side, front engine area, mounted rear of water pump. If the wires are worn or there is an oil leak near the switch location, replace it.

Inspecting all the above areas and replacing parts if needed, will fix your gauge issues.

Please rate and god bless:)

HI, the oil pressure sending unit may be malfunctioning at this point. this will cause erratic readings. if your oil level is proper and there are no apparent oil leaks, you will need to replace the oil pressure sending unit. this will fix the erratic oil pressure readings.

Concerning the gas gauge. this device also has a sending unit that sends the correct fuel level reading to the gas gauge via wire transfer. this sending unit is located and attached to the fuel pump assembly inside the gas tank. replacing this device will fix this issue as well.

Please rate and god bless:)

Hi, sounds like you have checked everything properly and you have a bad tank sender, current when checked with test lamp should pulsate.I suggest replace fuel tank sender.

Repair or replace the sending unit in the tank.

When replacing the fuel tank often mechanics dont check the gauge, it can be damaged when reinstalling it or if it came with the sendor in it already, often they get knocked around in shipping making them read wrong. And in the shop we always check the oil pressure with a live gauge . you can get one at a local parts store pretty cheap, it comes with a new sending unit and all, and the sending unit is the ground, the gauge has a continuous hot and the sending unit applies a amount of ground to allow the needle to climb.