97 gti gauge problems

[mboone71292]

hey guys, I have a 97 gti I purchased Last summer. When I got it the fuel gauge worked and so did the oil gauge. The speedometer has never worked since I got it. After a few trips the fuel gauge quit working however the oil light still works. I have checked the fuel sending unit and it seems to check out fine going into the mpem. I checked the gauge and it works when I apply power and put a ground on the sensor wire. Am I missing something or is the mpem the only thing between them? I also see the speedometer goes through it. Thoughts anyone?

 

[All Things Custom]

Did you test the sender with a vom on the two wires coming from the top?

The only thing it gets from the speedometer is power and ground.

The purple wire is + and the brown is - so if neither of the gauges are working then you are not getting power from the MPEM it seems. Check all fuses in the MPEM and test the purple and brown wires coming from it with the ski on.

 

[mboone71292]

I have power going to the gauges. The fuel and speedo both go the the mpem and are getting lost somewhere inbetween. Thoughts?

 

[All Things Custom]

Im confused..... The fuel gauge does not get anything from the MPEM but power and ground.

You should have
pink / pink-black = direct to fuel sending unit
blue / blue-black = direct to oil sending unit
purple / brown = + and - go directly to the MPEM

And a purple / brown I think, to supply power and ground to accesory gauges.

If you pull the plug apart at the oil sender connection (blue) the oil light will come on... If you use a wire and short the two wires coming from the gauge the light will go off.

if you pull the plug apart at the fuel sender (pink) you will show empty... if you loop from one wire to the other coming from the fuel gauge you will show full. ( it takes a few seconds for the gauge to start moving so be patient or turn the ski off and back on) (tap the start button without the key on the post)

Now the other end of the fuel plug going directly into the baffle (about 5 inches long) place red from VOM on one side and black to other. if you have gas in the tank you will show resistance. if you have gas in the tank and it shows open then you have a baffle problem.

After doing these tests let us know what you find.

 

[mboone71292]

The pink wire goes directly to the mepm and there is another set of wires going to the fuel sending unit. I found corrosion on the mepm plug and now the fuel gauge works. The oil light has always worked. Now I'm down to the speedometer. I think I have a bad sending unit. It looks like it is nothing more than a magnetic contact with a magnet spinning on a wheel making a pulse that varies with speed. When I hook my meter to it it just reads wide open.

 

[mboone71292]

The pink wire goes directly to the mepm and another set of wires goes to the fuel sending gauge. I found some corrosion on the mepm connector and after cleaning it the fuel gauge works. The oil light has always worked. Now all that is left is the speedometer. It looks like all it is a magnetic contact with several magnets spinning on a wheel. I believe it should pulse open/close if you spin the wheel real slow and watch it with a volt meter. any thoughts on this?

 

[All Things Custom]

Hmmmmmm Well thats a first for me.... ive never seen that configuration. Sorry for the bad advice then....

 

[mboone71292]

beats me

:hurray:beats me too. any way the speedometer is the only problem left...do those speed sending units go out often?

 

[kustomkarl]

You should get resistance with the ohm meter when you spin the wheel on the sender. If you not getting any resistance the sender is bad. I see lots of these thing going bad...well people are always asking how to test them, so it depends on how you look at it. Not everybody has a bad spedo sender...lol

Karl

 

[mboone71292]

Thanks... I think your right. I will order a new one today

 

[kustomkarl]

When you get the new one, give it a check to see the resistance the old one should have just for giggles.

 

[mboone71292]

That fixed it...Thanks guys.

 

[kustomkarl]

That is great news! Now go out and have a good time ridding it! Post some pictures if you can so we all can enjoy your ride too.

Karl