Dembo

As I understand it, the signal from the gearbox goes through that light blue connector at the back and then splits into two, one to the ECU and one to the speedo. You'd expect a speed converter to be between that point and the speedo, perhaps behind the dash.

But I seem to have another speed converter (the black box in the hole top left) that's wired into the blue/white wire that goes from the body loom to the ECU. That can only affect the input to the ECU.

Is the VSS itself the same for all models? I'd have expected all the VSSs and ECUs to work the same, especially as UK models can display both Kms and miles. The bodge for JDMs should be because they can only display Kms you need to fool the speedo and only the speedo.

So why would you want to fool the ECU into thinking you're going a different speed than you are?

I'm so confused. Where are you Bibbs?

Dembo

Okay it's obvious now I think about it.

Does it not change the behaviour of the ECU in some subtle way? I.e. change the way the engine runs based on speed, or is the ECU not that clever?

Shipley

Dembo - where abouts in the car is this exactly ?

Mine's a JDM so its a good photo for reference

Dembo

It's next to the ECU in the passenger footwell.

Shipley

fyi I had a P00050 error the other day. My speedo dropped to zero and it threw a CEL.

I tried a replacement speed sensor I knew was working but the fault happened again several days later.

I looked closely at the gearbox and saw an aftermarket little box which was wired into the loom which goes from the loom itself to the gearbox via the standard connector underneath.

I removed this, rewired the car to standard and the fault disappeared. It now reads Kms on the speedo while I source a replacement converter. They contain a resistor which changes the pulses so the car reads MPH and not KPH.

I'm not sure whether all JDMs have it fitted there (depends on the importer I guess) but for reference - thats where mine is

Most modern cars take the speedo reading off the ABS sensor - unusual to find the S uses the 'traditional' method.

Nice to isolate and fix a fault yourself

Paper Lawyer

Does my yellow jacket thread help at all, Dave?

https://www.s2ki.com/forums/index.php?showt...dpost&p=6023367

Dembo

If you could just send that to last month, it'll be really helpful.

Actually that thread was where I worked out as much as I had. The speed signal divides into two, and I couldn't understand why my converter was after the split. I realise that converter is to fool the ECU into making the speed limiter 180mph instead of 180kph, and I must have another converter (behind the dash probably) for the speedo.

Shipley just has the one converter. I read something saying the speed signal also went into the power steering ECU, so if you had a converter at the gearbox end it could affect the behaviour of the EPS.

Bibbs

A convertor/delimiter will usually have 4 wires. Power, earth, speed in, speed out.

The speed in signal (kmph) is divided by 1.6 for the speed out (mph).

You want to confuse the ECU to get rid of the 180kmph (112mph) limiter.

Bibbs

A lot of cars have speed sensitive PAS. To make the car lighter at low speed.

By dividing the speed by 1.6, you'll not have the PAS working at Honda's setup limits.

I went through quite a few of these on the old MR2. I ended up taking out the black box type, and replacing it with an Apexi RSM. You then keep the dash in kmph, but can delimit using the RSM. (I then swapped the clocks to UK spec ones with both kmph and mph).

On my S, I had the RSM working fine (it was still limited). The AEM got rid of the need for that. I also have UK clocks (from the prev owner).

Shipley

It does.....as soon as my speedo dropped to zero - the EPS light came on, swiftly followed by the CEL.

Makes for an interesting experience when you are on a bend at full pelt and the EPS drops out !