Speedo Problem 1998 Griffith

[Tom The Cat]

speedometer problem with my 1998 Griff

Hello all,

for nearly 4 years almost no problem with my Griffith, but now
the speedometer shows only 35 - to 40 miles, the needle remains virtually at the 40 miles Position stand, even if I drive faster.
Once the Needle stucks .... a light beat on the Dash and it falls down ... (only one Time)

Have not checked yet, only wanted to ask you.

My guess:

1. The sensor on diff. , but the Speedo-Needle shows a Value ..... should be ok!?
2. I read something in the Griff-Bible (Steven Heath) .... there is a fuse for the speedometer and light, etc., but if it were broken, then nothing would be displayed on the speedometer, right?
3 The speedometer itself? How can I check this Speedo , if necessary?

how can I find the most effective, the error .....

Many thanks to you and your suggestions links etc
TTC

[EGB]

Check wires on the drive shaft sensor. The plug and socket connection get's very dirty from road dirt. Also speedo earth points.

[steve-V8s]

The sensor is mounted at the right had side of the Diff. It is a coil with a pole piece at the end which looks at some teeth on the Diff output shaft. I would say the sensor is probably working correctly if you are getting any reading atall but it may be worth checking and adjusting the gap. It really needs to be quite small but don’t let it touch or it will quickly be destroyed.

The sensor produces a fairly weak sign wave output, this goes to a nondescript box buried somewhere in the spaghetti of wires behind the dash. The box converts the sensor signal to one that the speedo can understand. There is also a feed to the ECU which is used to control the throttle bypass stepper motor to prevent stalling. When you come to a halt the tickover should remain slightly high and then reduce in stages. If it is doing that then the speedo feed signal is probably good.

Sounds to me as if you have a mechanical issue with the speedo itself. Best way to find out is with an oscilloscope.

[GlynMo]

Without wishing to hijack this thread,I seem to recall reading somewhere that Steve Heath was going to produce an alternative to the TVR bodge for cars with the T5 gearbox. Does anyone know if it materialised, or is going to?

[QBee]

steve-V8s said:

The sensor is mounted at the right had side of the Diff. It is a coil with a pole piece at the end which looks at some teeth on the Diff output shaft. I would say the sensor is probably working correctly if you are getting any reading atall but it may be worth checking and adjusting the gap. It really needs to be quite small but don’t let it touch or it will quickly be destroyed.

The sensor produces a fairly weak sign wave output, this goes to a nondescript box buried somewhere in the spaghetti of wires behind the dash. The box converts the sensor signal to one that the speedo can understand. There is also a feed to the ECU which is used to control the throttle bypass stepper motor to prevent stalling. When you come to a halt the tickover should remain slightly high and then reduce in stages. If it is doing that then the speedo feed signal is probably good.

Sounds to me as if you have a mechanical issue with the speedo itself. Best way to find out is with an oscilloscope.

I think the gap is 11 thou IIRC

[Tom The Cat]

Hi All,
I took the jack (DIY) ... crawled under the car ... and you know, you see nothing, lying under the car, etc.
.... put my arm through the lower wishbone ... and wiggled around on the sensor ...... and hoped that maybe it would be good now.
Took a test drive and it all works great again.

So, there was a connection or pollution problem-

I think I should even have to check on the lift to all electrical connections respectively to clean again.

Ok, thank you for your help, TTC

[Argent]

GlynMo said:

Without wishing to hijack this thread,I seem to recall reading somewhere that Steve Heath was going to produce an alternative to the TVR bodge for cars with the T5 gearbox. Does anyone know if it materialised, or is going to?

I seem to remember that Blitzracing is looking at developing a replacement.

A.