instrument cluster wiring -which is speed signal

[eddyvr4]

Does anyone have a diagram or knowledge of which wire on the back of the instrument cluster is the speed signal?

I want to install one of the (Jaycar kit) speedo correction adjusters, in behind the dash, not in the engine bay..

my speedo is now out a bit with 235/40/18s

 

[bradc]

It won't be out that much. In fact, I found that with the stock 225/50/16 (rolling rad 1983.6mm) tyres on mine my car was slightly optimistic. With 235/45/17 (2021mm) my speedo and odometer read spot on. 235/40/18 is 2027mm and is probably very close to what your car is actually doing.

Have you confirmed it with gps or a stop watch and a 10km straight or something?

If your car is actually out, I do have a link on my home PC with all the details and wiring diagrams but it isn't on my laptop. When I'm home tonight I will try to remember to give you the link. (I'll most likely forget though!)

 

[eddyvr4]

Im running new sumitomo HTR ZIII with rolling circumference stated on the web at 1960mm, but 'seat of the pants' test seemed like the speedo changed very markedly, going to these from the stock tyres, which still had good tread, but clearly were a smaller diameter. (which doesnt add up if you say they are 1983mm rolling circumference.)

your right though, i need to get a GPS and check it, but it just feels waay out, so i assumed it was. Or maybe the car is much slower than it feels! (hope not!) ill go home and physically measure the rolling circumference myself tonight, on both old and new.

 

[matchtheclown]

GPS it or time it or just cruise next to someone you know who has a new car with stock wheels.

 

[SiliconAngel]

just cruise next to someone you know who has a new car with stock wheels.

Calibration against a known inaccurate device is utterly pointless