quick help needed - speedo jumping

[gesta1t]

hey guys... was just on the way to get a warrant and the speedo started jumping...sometimes it is completely dead other times jumps up to the right speed or just jogs up and down 20 -40km any advice?

car is a 1996 manual galant vr4

[karlous54]

take the surround off which is around the speedo and give the speedo a push and pull and see if that affects it at all. If not i found that there was a seperate earth wire on the back of mine that had come loose. If none of these work, then check that all the screws on the back of the speedo are failry tight ( not overly as you will crack something ) as some of the scews on the back actually power the dials and lights. good luck

[gesta1t]

take the surround off which is around the speedo and give the speedo a push and pull and see if that affects it at all. If not i found that there was a seperate earth wire on the back of mine that had come loose. If none of these work, then check that all the screws on the back of the speedo are failry tight ( not overly as you will crack something ) as some of the scews on the back actually power the dials and lights. good luck

cheers...just replaced the speedo sensor, still happening, will check those screws, where exactly is this ground wire you mention?

[VR4 MAD]

Mostly likely the Ignition Failure sensor is on it's way out. Total failure usually takes both Speedo and Rev counter out. Not sure what it does to the general running of the car in that case. Might go into limp home mode, not sure.

In my case, I lost the Speedo first and some weeks latter the Rev counter stopped working too. But the car ran just fine. The sensor is located on the front bank cam cover under the plastic engine cover. It's a small black box that looks like this:

40721

Hope that helps.

/toycar

[VR4 MAD]

Mostly likely the Ignition Failure sensor is on it's way out. Total failure usually takes both Speedo and Rev counter out. Not sure what it does to the general running of the car in that case. Might go into limp home mode, not sure. In my case, I lost the Speedo first and some weeks latter the Rev counter stopped working too. But the car ran just fine. The sensor is located on the front bank cam cover under the plastic engine cover. It's a small black box that looks like this:

40721

Hope that helps.

/toycar

PS Here's a photo of the sensor in place:

40722

[rayray24]

Mine does the same thing, but I'm blowing fuses and it only ever happens when I'm boosting in 2nd!! Maybe this is something I should look at to.

[GalantOnly]

/Hmmm
The ignition failure sensor is only wired to the rev counter in the dash, not speedo.
The speedo works only by 3 wires - 12V ignition, ground and speed sensor signal. That's it.
If 12V ignition feed was a problem, the whole dash will go out - so it's isn't a case.
If ground and speed sensor is good, then it could be PCB on the back of the dash, that's damaged

[VR4 MAD]

Interesting.................. :shocked:

I stand corrected ........... :coat

That doesn't explain how by just replacing the IFS I got both back working though........... :huh2:

/toycar


/Hmmm
The ignition failure sensor is only wired to the rev counter in the dash, not speedo.
The speedo works only by 3 wires - 12V ignition, ground and speed sensor signal. That's it.
If 12V ignition feed was a problem, the whole dash will go out - so it's isn't a case.
If ground and speed sensor is good, then it could be PCB on the back of the dash, that's damaged

[GalantOnly]

But... You never know:) I'm just looking in wiring diagrams /yes

[gesta1t]

ok so just put a different speedo cluster into it...same thing still happening...anymore suggestions?...thats the speedo sensor replaced, checked plugs from it in engine bay, and a different dash unit tried, anyone know about this earth wire out of the dash?

[VR4 MAD]

Going by what Alex (GalantOnly) said above, then it's not the IFS but the speed sensor that might be the root cause as you have eliminated the gauge cluster by trying another and the problem remained, correct?

Not sure where the speed sensor resides though, sorry. I'm sure someone will come along and tell us or try the search button.............. :)

/toycar

[GalantOnly]

This connector is where both speed sensor signal (pin 8, white/blue) and speedo ground (pin 16, black) goes throu to the dash.
The speedo ground wire is grounded to the chassis in the middle of the picture

PS: this connector is around coin box

[scottie2hotti]

I'm pretty sure the speed sensor is located under the air filter box on top of gear box theres a plug there. IIRC

[gesta1t]

yeah it is...jsut in front of the rear engine mount...i've already replaced the speedo sensor