[Jon]

Just curious, is the Temp circuit similar to the fuel gauge where one could ground the single wire and have the needle move +

[dave-r]

Probably. Good idea Jon.


Wayne try putting the wire on a good ground connection on the block and switch on the ignition just for a couple of seconds to see if the temp gauge swings all the way over. Don't leave it switched on though or you will burn the gauge out. That will tell you the wiring is OK to the gauge.

[RedRaven]

Ok never done either.

What switch on the ignition? and can you post an example pic of the earth on the block.

cheers.

[dave-r]

Wayne. You really shouldn't be working on cars by yourself mate.

Just hook your wire back up to the sender and see if it works. Keep it simple.

[dave-r]

http://challenger.mpoli.fi/forum/viewto ... ?p=193#193

The engine block and the complete chassis/body etc should be electrically connected to the negative of the battery. This is called chassis ground or earth.

So connecting to any bare bit of metal on the engine or body should be connecting you directly to the negative side of the battery. This is what is called "grounding".

When I say "switch on the ignition" I mean turn the ignition key to the "run" position where all the instruments will power up. Including the temp gauge.

[RedRaven]

I feel Daft as fook.

[dave-r]

You could never be as daft as you look.

[RedRaven]

[drewcrane]

that is a 2 man job be very careful to only touch the ground area for 1 second, i fried a gauge and the little condenser that runs the gauge unit,if you burn that up you will have to pull the gauge/dash area,be care ful

[dave-r]

Yep so just turn on the ignition long enough to see if the gauge starts to shoot up. then switch it off straight away.

[Jon]

yep I should have that one.......I should look for one on ebay eh?

Here you go.

http://cgi.ebay.com/ebaymotors/CUDA-CHA ... 53e01619c5

[dave-r]

Only if you don't have AC Wayne which I can't remember. You would need different spacers to go with that bracket too. Easier to buy a complete kit.

[Eddie]

www.bouchillonperformance.com They have everything you would possibly need Wayne all exact re-pops with attaching bolts and the spacers, ect I've dealt with them before and they are first rate. You can buy as little as you need or the complete kit, prices are reasonable. They ship International too. Click on alternator brackets

[RedRaven]

Ok so decided to try and sort this out again.

Ade and Drew have assured me that I will never be able to cook it due to the mild to cold temp over here so it wasnt a huge issue.

Anyway I was lucky enough to be given a section of harness from Drew and it had the exact purple cable I needed in perfect condition.
So I stripped it out from the bulkhead connector and gave the connector pin a good clean down with some sandpaper for a solid connection and wired it up to the existing section of harness and also to the temp sending unit.
I turned her over for a wee bit but the gauge did budge so the problem must be with the gauge.

Bummer as to get to it will be a problem as Ive not done this before.

[Adrian Worman]

I got some spare gauges Wayne, sort em out when you get over here

[RedRaven]

Cheers Ade, we will have to get you a bleedin cape to wear bud....

This is really bugging me now as a new TS unit and now the cable and still no joy.

On a trouble shooting note, what else could the problem be.

I may need to remove the stereo to access the back of the gauge or is this neccessary?

Is there another way I can get to look at the gauge with taking too much apart?

[dave-r]

Does the fuel gauge work OK?

You might be able to get to the back of the gauge from under the dash.

[dave-r]

Was the engine definitely up to full temp when you tested the gauge?

[dave-r]

I would imagine that to test the gauge you could just touch the sender connector to a ground. You should get full deflection. But be careful just to do it for a second or two as you could burn the gauge out.

[RedRaven]

I would imagine that to test the gauge you could just touch the sender connector to a ground. You should get full deflection. But be careful just to do it for a second or two as you could burn the gauge out.

Dave, could you run me throught this please.

So have the car started and running, then use a nail to connect to the runner ended head and touch it off the body of the car ,for a second or two, to see if the gauge jumps is that the idea. If the gauge jumps this tells me that the problem is not with the gauge, could it be a fuse issue?

[RedRaven]

Ade phoned me so I got the low down on the test.

[dave-r]

I think the fuel and temp gauges are just ohm meters that measure resistance to ground. At least I kind of remember it being that way.

Your temp sender is a resistor between the gauge and ground. As it heats it's resistance lowers and the gauge goes up. If you take the wire and touch it to ground you should peg the gauge hard over to hot if I am right about how it works.

Sorry I have trouble remembering this stuff.

[RedRaven]

Ok so the issue cant be a fuse because one fuse does all of the gauges on the gauge for the fuel,temp etc. So the cable appears to be fine and defect free. so this points me back to the TSU itself. Could the unit be faulty.

Im going the turn the key to the on position and let the gauge come alive. then I going to put a nail up into the end of the rubber boot of the cable and touch it off the negative of the battery and see if the gauge moves at all. If it does the from the gauge, bulkhead connector, cable is fine which can only leave the TSU which may be busted.

How does this sound as a plan of action guys?

[dave-r]

Sounds good to me. But get yourself in a position where you can see the gauge from where you are grounding it. Extend the wire if need be. Any bit of bare metal and most screw heads will have a good ground.

If the fuel gauge works OK then the 5v power supply from the back of the dash must be working.

[RedRaven]

Well the further away from the gauge and dash the problem is then the earlier it will be to fix I suppose. If the gauge kicks on this test then it must be the TSU so I will get a new one.

I will get my brother to come with me and he can watch the gauge for any movement when I ground the cable.

[RedRaven]

Well I tried the cable and nail and no joy the gauge didnt shift a bit. I didnt have to time check if the boot at the rear of the gauge was making contact as the radio is just under it.

[Adrian Worman]

Unlikely that the power supply is nit connected.............sorry pal but you got a shagged gauge
I got spares tho

[RedRaven]

I would like to rule it out mate, its down to 2 remaining items, either the sender is fooked or the gauge.

[dave-r]

But you just tested it to rule out the sender????

You pulled the wire off the sender and grounded it right? The guage didn't move (you had the ignition on right?) so it is either the gauge not working or not connected to the sender wire or the low voltage power supply.

The wire will also go through the bulkhead connector. And as your exhaust spend many a day blowing directly onto that I would be double checking the wire is actually connecting through to the other side.

You have checked continuity of the wire with an ohm gauge yes?

[RedRaven]

I sat in the drivers seat and turned the ignition to on and I had the boot end of the cable that connects to the sender with a nail in it and touched it off the door arch but nothing moved on the gauge.