GTA Speedo & Digital Display issues

Hi All

My speedo rarely works at the moment. Sometimes it will work for a few seconds after hitting a decent bump in the road.

It used to work most of the time but serious bumps would cause it to stop for a few seconds.

Also - recently every time I start the car the digital fuel gauge and trip computer need to be reset using the "button with the dots" on the dash.

I am assuming the two problems are connected in some way.

Is this likely to be an battery earth issue?

If you think it is an earth issue, check your earths.

good earths are allways good to have.

You can run the fuel gauge in diagnostic mode. I doo, because it is a "live level reading" rather than a computed level reading.

See the workshop manual for how it all works.

Tom, there is a lot posted on this forum regarding intermittent speedo/fuel gauge problems, but it all seems to boil down to poor contact of the pins in the connectors immediately behind the speedo/rpm unit.
In the first instance, I would remove the steering wheel, the bottom cover of the binnacle, then the top cover, exposing the instrument cluster. There you will find various connectors going from the main loom to different points on the cluster. I would undo each in turn, spray the contacts of both male and female pins with a good contact cleaner, attach and detach a few times to scratch away any surface corrosion, re connect it all, dont put the covers back on, reattach the steering wheel, and go for a test run to see if your problems have gone. If all is well, I would try to anchor each side of any flying connector by passing a cable tie between the wires of each half of the connector and pulling tight, to stop any future movement of the pins, and it might also be worth sandwiching the connector/s between two pieces of foam, and trapped with the top cover, this should elliminate any movement caused by vibration and sudden jerks when going over bumps.
Give this a try in the first instance and let us know how you get on

John

I've got a unit in bits .I'll take some pics of the usual suspects .

I've got a unit in bits .I'll take some pics of the usual suspects .

Brilliant.....you have read my mind Lee.....earlier, and seeing you had one for sale, I thought of pm`ing you to do just that.....Thanks, Not having seen a turbo one, I understand from another member I have been corrosponding with about the same subject, there is a sort of "Y" lead going from the loom to the cluster, can you take a pic of that for me pse... from memory I dont think the Atmo has one, Thanks

John

[BIG_MVS]

Hmmm

Speedo will probably be the connector on the RHS of the unit, you can get to it by removing the RHS heater vent on the dash/binicle. Clean all the contacts and squeen the pins together with a small scewdriver to get better connections. Or some owners have ditched the block conector and soldered the wiring together which has totally sorted the issue altogether.

The fuel trip comp could be anything, what year is your GTA?

By the way JohnC - Merlins issue was sorted by changing the ecu over back to the original, if you remember the car had the flashing trip reading after a short while. I'll endeavor to send those TSU's as well very soon!!

By the way JohnC - Merlins issue was sorted by changing the ecu over back to the original, if you remember the car had the flashing trip reading after a short while.

Thanks for that feed back Martin, yes, we spoke about this on the North Wales Tour. I think a number of other members might be interested in this.

For those who might be,..... when another ECU is fitted to these GTA Turbos which is not the original one or a replacment of it, it should be noted that the Fuel Flow information for the computer is derived from the ECU, and it is possible that other ECU`s either dont supply the fuel flow information, or the protocol of the information is not recognised by the GTA`s computer, or perhaps the signal level of information is insufficient. However there may be some ECU`s that are combatable, in which case....no problem. But if problems occure with a flashing fuel computer readout after a different to original ECU is fitted, and after about 10 miles of running with it, it might be worth slipping the old one back in to see if the fault disappears.
Hope this is of interest. .

Dont forget to check the connector behind rear offside wheel for bad connections.
Mine operates for around 3 months then it's the same old procedure; instrument binacle off, LHS big square connector off, spray with switch cleaner & re-assemble. Then spray switch cleaner on the connector behind rear wheel.

Seems to do the trick.

oh, and also leave both air vents half out, so you can gain access and wiggle the bast&rd things when the needle suddenly takes a dive to zero

I also find that flicking the rear demister on and then off often brings the speedo needle back.

I've been into the binnacle with switch cleaner, too and regular sprays/wiggle of the connectors in the inside of the off-side rear panel behind the wheels and underneath the air filter (on the V6 Turbo at least).

Out of interest, how do you get the heater vents out without breaking them?

Jonc,

Good call, I was just about to ask the same thing.

Trevor.

All will be revealed ......... in the Members section

Hmmm

Speedo will probably be the connector on the RHS of the unit, you can get to it by removing the RHS heater vent on the dash/binicle. Clean all the contacts and squeen the pins together with a small scewdriver to get better connections. Or some owners have ditched the block conector and soldered the wiring together which has totally sorted the issue altogether.

The fuel trip comp could be anything, what year is your GTA?

By the way JohnC - Merlins issue was sorted by changing the ecu over back to the original, if you remember the car had the flashing trip reading after a short while. I'll endeavor to send those TSU's as well very soon!!

It's a 1988 model

The trip computer seems all good now.

Helps if you read the workshop manual!

Thanks everyone for all your tips. I'll give them a go in the Christmas holidays!

I gave the connectors behind the right rear wheel a wiggle and hey presto - the speedo now works!!!