Need a little guage wiring help

[Bostonian1976]

up in NH this weekend playing with the Rover - trying to sort out my guagea

1) the temp guage (vdo) doesn't work at all. There's a green/blue wire that runs to it from the sensor. Probaly a bad sender

2) oil presssure guage - (vdo) - this is the one I need help with. There's two wires coming off the sender - one goes back to the guage and the other is disconnected. The brown wire that is connected runs back to the guage - there is also a ground wire coming off the guage that is properly grounded. Are those the only connections I need?

3) fuel guage - (original) - goes to full and stays there. I checked the ground on the tank sender, the sender connection, and the connection to the guage itself. The only other wire coming off the guage is one that goes to the dash lights switch

Any help would be appreciated.

[scott]

2) oil presssure guage - (vdo) - this is the one I need help with. There's two wires coming off the sender - one goes back to the guage and the other is disconnected. The brown wire that is connected runs back to the guage - there is also a ground wire coming off the guage that is properly grounded. Are those the only connections I need?

i don't have the eletric oil prsr gauge. but i'd bet the disconnected wire needs to make it to the fuse box, side that's hot when ignition switch is on.

[siiirhd88]

Typical electric gauges use the sender to vary the resistance to ground, changing the gauge reading. I don't think the VDO use a voltage stabilizer on the power to the gauge as do the British Smiths and Jaeger gauges, but your fuel gauge should use one. Power should come from the factory green colored wire, which is fused power with the ignition switch on. Generically, the power wire should connect to one terminal on the gauge, and the other guage terminal has a wire run to the sender.

The VDO oil pressure sender usually has two terminals, one is for the gauge and one is for a low oil pressure warning light. The light is wired like the gauge, power to one light terminal, then a wire from the from the light to the other sender terminal. The light usually comes on at about 7 psig oil pressure.

The fuel gauge is wired the same, using a voltage stabilizer on the power to the gauge. As the fuel tank level rises and lowers, the tank sender varies the resistance to ground causing the tank level indication to change. The strongest ground is when the tank is full.... If the guage reads full all of the time, there could be a ground anywhere along the green with black trace wire that runs from the gauge to the tank sender. With the ignition switch on, try removing the green with black trace wire from the tank sender. If the fuel guage reading lowers, there could be a ground along the wire length, the sender could be bad, or the wire is on the incorrect sender terminal (some tank senders hava a low fuel level light terminal). Holding the wire against ground, like the chassis rail, should cause the gauge to rise upscale.

The water temp and oil pressure gauge can be tested the same way as the fuel gauge. Unplug the wire from the sender and hold it to ground. The gauge reading should rise upscale. If not, check power to the gauge.

Hope this helps,
Bob

[Daurie]

On the oil pressure guage I'd say the disconnected wire on the sender would need to go to switched 12V+ since the circuit is grounded at the guage. I'd test it first by putting the disconnected wire to the battery pos and start the engine, should have oil pressure on the guage. Might be good preventative measure to wire in a temporary 3 amp fuse before going straight to the battery.

The fuel sender may be bad. I've seen them (non rover) short internally and read full regardless of level. Sounds like you've checked everything but sender. If you have an multimeter pull the sender and check the resistance while having a helper move the float up and down. The resistance should change.

[Bostonian1976]

thanks guys. I don't think I have a voltage stabilizer anymore....maybe that's my fuel guage problem

as far as the others...who knows. I just couldn't get them to work....

time for new senders maybe...

[Bostonian1976]

On the oil pressure guage I'd say the disconnected wire on the sender would need to go to switched 12V+ since the circuit is grounded at the guage. I'd test it first by putting the disconnected wire to the battery pos and start the engine, should have oil pressure on the guage. Might be good preventative measure to wire in a temporary 3 amp fuse before going straight to the battery.

The fuel sender may be bad. I've seen them (non rover) short internally and read full regardless of level. Sounds like you've checked everything but sender. If you have an multimeter pull the sender and check the resistance while having a helper move the float up and down. The resistance should change.

so I should have a positive running to the sender? maybe that's my problem...

I'm not sure where it was meant to hook. It is one of those 'u' shaped connections that looks like the others at the grounding point.....

[Daurie]

From the way you describe it the grounded side of the circuit is at the guage. It goes from the guage to the sender and then back out of the sender with the unconnected wire right? Sounds like the only way to get voltage into this circuit would be into the unconnected wire. I don't know anything about VDO guages and how they are supposed to be hooked up so this advice is coming from a logical view of your situation, also given that the existing connections are as they were intended.