speed signal

A

aidan

Member +
Where does the ecu get its speed signal from my ep71 (4e) is not hitting speed cut at the usual 190k on the clock and is throwing up the eml
 
dac69er

dac69er

Super Moderator
i dont know if yours is different, but the ep82 and ep91 speed signal comes from the speedo.
 
Stu-

Stu-

Member +
There is a reed switch inside the dash speedo that has an output wire that runs back to the ecu.
From memory its a square wave signal.
 
Stu-

Stu-

Member +
It will depend on what year EP71 you have as their are three different loom configurations but if you look at the dash plug behind the stereo its the yellow wire with the blue stripe. Looking at the back of the plug on the engine loom its second row down, second one in.

Also assuming your EP71 was EFI originally and not carby
 
T

TRD1mos

Member +
What do you want to do to help you with?Do you want to get off your speed limiter?Please before you answer,give me information about your ecu (EP82,EP82 ATM,EP91,EP91 ATM).If so with a simply switch without lamp (led or any) just on/off you can dissable it.The expensive way is with a speed limmiter cut off like Greedy or Apexi Rev Speed meter that can be done by buttons.My opinion is not to interfear with your wires from cluster,you can do it very easily to your ecu wires.
 
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A

aidan

Member +
It's an 1989 ep71 turbo s I have with a 1995 ep82 4efte.. I just want to find the speed signal coming out of the clocks so I can give it to the ecu to knock off the engine management light as the light is coming on when I go over a certain speed
 
weeJohn

weeJohn

Lifer
Work back from the ECU, its the wire labelled SPD on the ECU and it will run straight back to the dash cluster. Loads of info in here on EP82 wiring but it may not suit your conversion completely.

http://www.toyotagtturbo.com/wiki/EP82wiring/EP82 Starlet Wiring and Connectors.pdf

On the MK1 GTs, there was a very easy mod to do to remove it, there was simply a switch in the speedo that gave the ECU a signal when up to speed cut speed, it was just a matter of bypassing that switch. You may not have that on your EP71 clocks, I just dont know, but it can all be traced out easily with a meter.
 
dark_knight

dark_knight

Member +
now that we are on the topic, doesn't the ECU need speed readings for other reasons, not just to speed cut..? for instance, when having revved past point-x for longer than time-y without getting a change in signal from sensor-z -- i'd like to imagine so..
 
R

Rev

Member +
You might be on to something there. I know an auto box can have a sensor on the box that compares itself to the vehicle speed sensor for gear lockup and also acts as a back up if the box sensor fails.
 
weeJohn

weeJohn

Lifer
They will all have a speed signal, usually square wave as someone said above. Speed cut was operated by a seperate switch in the speedo on Mk1s rather than from the ECU calculating it from the pulses, as the EP71 came before, it may also have the same.
 
K

ktsirigotakis

Fresh Recruit
hi guys does anyone know what is the frinquency that the dash speedo generate. i have read somewere that it start to send puls from 80km/h
 
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