Speed Sensor Wiring

[MrOizo]

Can someone tell me if i can some how bypass the "ODO and TRIP METER" from this diagram.

Reading up on the ODO and Trips function is to "Buffer" the signal. I have no idea what this is.

The ECU gets its feed (Pink) from the ODO component.

Any help appreciated!

[KinLoud]

Buffer may mean - provide extra current... OR - change the shape of the waveform.

Can you try hitching it up directly?
My experience with my AA63 Carina... factory 4age bluetop got speed signal from a reed switch inside the mechanical speedo display. Signal was a square wave.
The gen3 3sge was looking for a sinewave generated by a magnetic pickup...

Just connected the square wave direct to the 3sge computer and it was happy as!

Ken
Auck
021 408 863

[jaypines]

what car is that for? you might try bridging pins 5 & 6 of the odo/tripmeter and cut off the ground part (pin7). why do you want to bypass it?

[matt dunn]

From my speedo experience, all the pre 2000 toyota type ECU's all look for a square wave signal,

Normaly there is a signal from the speed sensor to the speedo itself, which can be any signal at any rate depending on the signal,
but the speedo itself outputs a square wave of a certain number of pulses per KM to the ecu.

And more correctly, the ecu outputs the voltage and the speedo head pulses the signal to earth.

[MrOizo]

Well the thing here is that i have gone from a mechanical speedo to an electronic one.

Apparently the cable spins the wrong way for the MK3 Supras.

Since i cant really run the speedo cable, i was going to run the Apexi RSM insead. Tried hooking this up to the output from the sensor itself - (L-R) and no luck.. didnt register speed.

Going by the diagram and reading that the sensor grounds for signal, could i hook up the RED wire from the sensor itself?

I'll get more info which has been written online and post here.

Thanks for help so far

[matt dunn]

post a picture of what type of speed sensor you are using and I should be able to tell you how to make it work,

anything like this one?

http://www.linkecu.com/support/dlandswu ... peedSensor

[jaypines]

looking at the diagram, the red wire is connected directly to ground. i reckon square wave signal would be from the blue-red (l-r) wire with an amplitude of 12V. try hooking it up with oscilloscope and see.

[MrOizo]

Here is the info that i have been given from a site:

Pin: 2
Colour: Blue - Red
Main Description:Vehicle speed signal for speedometer & odo trip meter #77
Explination:This signal goes to the speedometer and the odo and trip meter. The odo and trip unit will distribute the signal (buffer it). Blue - Red

Pin: 8
Colour: Red
Explination:Vehicle speed signal sender ground #77 Ground for the vehicle speed signal sender.

Pin: 23
Colour: Yellow
Explination:IG (plus) signal for alternator #68
Gauge (plus) for vehicle speed sensor #77
Gauge (plus) for backup light #116

Here is a pic of the sensor (one on the left):

[MrOizo]

Pin: 2
Colour: Blue - Red
Main Description:Vehicle speed signal for speedometer & odo trip meter #77
Explination:This signal goes to the speedometer and the odo and trip meter. The odo and trip unit will distribute the signal (buffer it). Blue - Red

Pin: 8
Colour: Red
Explination:Vehicle speed signal sender ground #77 Ground for the vehicle speed signal sender.

Pin: 23
Colour: Yellow
Explination:IG (plus) signal for alternator #68
Gauge (plus) for vehicle speed sensor #77
Gauge (plus) for backup light #116

Well got under the car today and can only confirm that i had power on the yellow. No pulses from either of the other wires when the wheel was turning. :/

Hmmm....

[postfach]

A digital multimeter may not be able to pick up the pulse. Have you got it set on AC or DC?

How are you turning the sensor?

[MrOizo]

was simply a test light off both of the red and blue-red wires.
Was told to try this. is this like an induction type pick up rather than a reed? (thats if they are like that?)

Prob not a good test but was told to give that a shot.

[matt dunn]

Those type of sender are crap,

well they crap out all the time, have been on Hilux's and AE101's etc etc.

They all use the same head with a different length shaft and gear.

I was playing with one the same on a GT4 a while ago, but cant remember what pin was what off the top of my head.

[matt dunn]

But that diagram does not look right for that sender.

Sender should have
a power feed ( 12v or 5V from dash, cant remember)
an earth,
and a signal wire.

[MrOizo]

But that diagram does not look right for that sender.

Sender should have
a power feed ( 12v or 5V from dash, cant remember) Yellow and is 12v
an earth, Red
and a signal wire.Blue-Red

Well managed to sort it out. all it needed was a ground and a re-wiring at the ECU to give it a feed.

Chru chur~!

Thanks for help peoples.

[rollaholic]

for future reference if you are using a filament type test light, alot of ECU type signals wont activate it as they are around the 5V mark. you need an LED type test light.