speedo problem

[rottweiler]

I've got a 1998 chim 450. The speedo and mileometer have both stopped working. I have read the previous posts and checked the wiring behind the clock. I do have a 12v to the green wire, a good earth on the black wire and don't know how to check the yellow pulse wire. I have also been under the car checked the sender on the diff, cleaned it all up and reset the gap to about 1mm from the toothed wheel.
I STILL HAVE NOTHING on the speedo or mileometer.

Is it time to buy a new sender or is there anything else that I can do.
The sticker on the back of the speedo says CAERBONT AUTOMOTIVE. Anyone know a good place to buy an appropriate sender?
cheers

[s27]

rottweiler said:

The sticker on the back of the speedo says CAERBONT AUTOMOTIVE.

Caerbont site at www.caigauge.com/Caerbont_Automotive_Instruments.htm

also trade as speedy cables

www.speedycables.co.uk/

do repairs and recallibration may be worth a call for the sender

SP

[SwanJack]

My speedo/odometer is currently with speedy cables being stripped down and repaired. They work out of the same unit as caerbont automotive. They quoted me between £40 and £60, 21 day turnaround. Carriage is on top but being 'local' I can collect.

>> Edited by SwanJack on Sunday 12th March 11:24

[paulathome]

I have a similar problem with my 1998 chim 4.0L.
I bought the car three weeks ago and the speedo started going intermitent on Sunday then stopped last Tuesday.

You need to check that you have a pulse comming back from the sender unit you have just been adjusting.
Jack the car up and run the engine with both rear wheels off the ground in gear, preferably 1st gear.
If you can get hold of a multimeter (better still an oscilloscope) the voltage should go from 12volts to zero, albeit very quickly. (Ten pulse per propshaft rotation)
This will probably show as a gradule increase in voltage the faster the prop is spinning. (because the meter will not be able to react fast enough to the change in voltage)
If you do get these pulses then the speedo head is probably faulty, if not then a new sender or dodgy wiring
between sender and speedo are the next bits to check.
Check that the contacts are OK at the sender and are not corroded.
I hope its you sensor or wiring and not your speedo head, its a lot cheaper.

I have all this work to try in the next couple of days, I was going to do it today but its been snowing here
all day and the temp here is minus 3 degrees C. Not happy.

Let me know how you get on and where you got your bits from and I'll do likewise.
Hope this helps.
Cheers Paul.

[justinbaker]

Try winding it down to a smaller gap than 1mm before anything further, mine worked when I thought I was getting too close.

[Steve Willson]

My speedo works fine, apart from the Mileometer,it has stopped on 49000 is there anything i can check before starting the job of dismantling the dash and removing the speedo for inspection / repair?

[rottweiler]

jacked the car up and had the wheels spinning in 1st gear. Put a multmeter on the speed sensor wires.
Could only get a reading when the multimeter was set to AC. Don't know if this is correct.
Didn't want the wheels turning too fast - all a little bit scary!! -but the meter voltage was showing up to 0.6v. (1st gear about 3000 rpm) It definately got less when the wheel speed decreased.
Does anyone know if this sounds about right?
Would it be worth doing the same but putting the meter on the pulse wire at the clocks - thinking that this might check the wiring.
If so would you connect the meter to the pulse wire and an earth?

[s27]

Steve Willson said:

My speedo works fine, apart from the Mileometer,it has stopped on 49000 is there anything i can check before starting the job of dismantling the dash and removing the speedo for inspection / repair?

Quite a common problem,either leave it for a short period and it may re start, or whilst driving along give cover a few sharp taps / and /or repeatedly press reset button for trip ometer. There ahave been numerous posts with problem at 9999? miles. Above cured mine when it happened.

SP

[mrsflipflopgriff]

The transducer gap needs to be 8 thou or less for it to work.
FFG

[Parrot of Doom]

rottweiler said:

The sticker on the back of the speedo says CAERBONT AUTOMOTIVE.

At least it doesn't say "Oh no, not again!"

[Painey]

'Speedy Cables'. Gotta love the irony in that name as they're anything but speedy. I mean 20+ working day turnaround for a speedo repair!!! That's a joke.