[Mk2] [Turbo] Engine management light

[Jaffacake]

Disconnected my speedo cable at work today in preparation to change clocks when I got home and on the way home in the p1$$ing rain my engine management light came on, no change in the vehicle driving wise just wondering if anyone thinks it could be rain/ speedo cable related or something worse. Cheers guys

[Rogue]

Yes, disconnected speedo = engine management light. It won't affect the car in any other way, with the exception that the built in speed limiter is now disabled.

[Jaffacake]

Yes, disconnected speedo = engine management light. It won't affect the car in any other way, with the exception that the built in speed limiter is now disabled.

Brilliant thanks for putting my mind at rest massive relief. My next question is iv just takenmy old clocks out 110mph ones and replaced them with 160mph clocks will the speedo be cocorrect or do I need to change something else too.will do a run to work in morning with sat nav to see how accurate they are.

[Rogue]

UK speedo will read correctly and will clear the engine management light. You will still have the limiter in place at ~112mph.

[Jaffacake]

UK speedo will read correctly and will clear the engine management light. You will still have the limiter in place at ~112mph.

All worked fine when compared speedo to sat nav. How do u remove speed limiter tho?

[jimGTS]

UK speedo will read correctly and will clear the engine management light. You will still have the limiter in place at ~112mph.

really?

[Ryan S]

UK speedo will read correctly and will clear the engine management light. You will still have the limiter in place at ~112mph.

All worked fine when compared speedo to sat nav. How do u remove speed limiter tho?

device on the rear of the clocks, quite hard to come by now, there was a guy who used to do them. check ebay etc...


edit: http://www.ebay.co.uk/itm/HKS-Speed-Lim ... 460809bc48

[toxo]

UK speedo will read correctly and will clear the engine management light. You will still have the limiter in place at ~112mph.

really?

Yes, because the 110mph speedo is a 160kph speedo with an mph face stuck over it, so there has been no electronic mph/kph conversion done. You can quite happily just swap speedo heads around (just the head, not the whole cluster) and they all read correctly, providing the electronics are factory. And if the electronics are factory, the speed limiter will still function.

[jimGTS]

UK speedo will read correctly and will clear the engine management light. You will still have the limiter in place at ~112mph.

really?

Yes, because the 110mph speedo is a 160kph speedo with an mph face stuck over it, so there has been no electronic mph/kph conversion done. You can quite happily just swap speedo heads around (just the head, not the whole cluster) and they all read correctly, providing the electronics are factory. And if the electronics are factory, the speed limiter will still function.

there is no 160kmph speedo


there is a 180kmph jdm speedo and a 160MPH speedo
so they are not one in the same scale wise (needle position).

i just queried how a uk speedo would work on a turbo ecu.

does ecu see 160mph as 180kmph in terms of 'needle position'? or does ecu still know even with 160mph uk clocks what kmph its doing.

[toxo]

Sorry, 160kph speedo was a typo!

The ECU only sees the VSS signal generated by the speedo head, which is just pulses. The pulse 'scale' doesn't change regardless of what units the speedo is made to display in. You could say that all the pulse signals from all speedos are in KPH I suppose. They aren't, they are in an arbitrary Toyota VSS scale, but that's the easiest way of explaining it.

[jimGTS]

Sorry, 160kph speedo was a typo!

The ECU only sees the VSS signal generated by the speedo head, which is just pulses. The pulse 'scale' doesn't change regardless of what units the speedo is made to display in. You could say that all the pulse signals from all speedos are in KPH I suppose. They aren't, they are in an arbitrary Toyota VSS scale, but that's the easiest way of explaining it.

you say "what unit the speed is made to display in", which to me still sounds like your refering to someone popping a 110mph dial over the original 180kmph dial face to do a simple conversion.

i am not refering to this, i am refering to a 160mph UK speedo with a jdm ecu.
the needle position on this will not be the same as a jdm dial, hence my queries.
its pulses will be different, EDIT or at least calibration, as needle at 12 oclock is say 90kmph on a jdm, and 80mph (or 130kmph) on a uk speedo, so entirely different scaling.

[toxo]

When I say "what unit the speedo is made to display in" I mean what unit Toyota manufactured the speedo to display. The VSS pulses coming out of the back of it aren't directly linked to what speed the needle is displaying, they are in 2 different scales. Like I said, think of it as though all the VSS pulse signals coming out of all speedos are KPH because all Toyota ECUs count in KPH regardless of what units their speedo uses.*

I don't know how else to explain this, but trust me if you put a UK speedo head into a turbo speedo cluster the needle will read the correct road speed and the ECU will receive the correct speedo pulses exactly as it did with the JDM speedo head.


* This is a simplification, VSS is a scale unto itself and is neither MPH or KPH

[jimGTS]

cool, guess thats answered it by mentioning 2 different scales.
1 for the ecu which is constant, and 1 for the "needle" dependant on the dial.

so guess needle is just "cogged" differently between them but signal sent is the same.

[toxo]

Yes It's why there's so much gubbins on the back of the speedo head, because it's also signal converting the signal from the gearbox speed sensor which is not VSS, into something the ECU can understand. Then on top of that the VSS signal also goes to the power steering ECU as that has to know how fast the car is going too!

The little 4-or-5-wire black boxes you can get from eBay to do speedo conversion mess with the gearbox speed sensor signal, so the signal is wrong before it even gets to the speedo unit to be converted. That's why Stef's clamping delimiters work better as they feed the correct signal to the correct circuits in the car.

[jimGTS]

can these delimiters still work on uk clusters?? so no or not much wiring differences back there?
obviously with uk na's, there is no speed limit so trying to work out if its still possible to fit one as after all speed is sent to ecu, and its ecu that cuts things off.

tbh, ive no real need for one, but be good to know.

[toxo]

No because they intercept the signal before the speedo. So the UK speedo would start reading at 0.6 speed.

You either need an HKS SLD to intercept the VSS at the ECU or a Stef Derner delimiter (which can work with both speedo heads, it's switchable) to do it properly.

[jimGTS]

oh i was refering to a stef delimiter, i bought one before on my old rev5.
i wouldnt buy a generic one from ebay.

just seeing whether a stef one would still fit exactly the same, as instructions would be refering to jdm clusters.

[toxo]

Stef ones do, they have a small switch on them to set whether your speedo is a kph or mph speedo and feed it the appropriate signal.

It's on the right: