AE111 SP1 signal

[johntramp]

Hey. The speed signal from the dash of an ae111 to the ecu, how does that work?
I have a 20v 4age in an ae85 and I want to make something to keep the ecu happy as there is no speed signal from this dash. Does it just take a pulse once per revolution of the speedometer cable or what?
Apparently a 555 timer will work but what interval do I want it to be at approximately?

Cheers

[matt dunn]

The correct signal is 4 pulses per revolution of the cable.

but as long as there is a signal of some sort the ecu won't care untill you reach the speed cut.

I have a unit that can be placed inline with the cable that produces the 4p output, but they are about $180 from memory.

Matt

[johntramp]

Cheers.

I see you have a similar engine. Did you use the unit inline with the cable in your Corolla?

Is there any benefit for the ECU to have an accurate reading?

[johntramp]

also, are they 12v pulses?

[KinLoud]

My understanding (Matt Dunn please correct me)....
The computer supplies the power and the "pulses" are just where the speed sensor connects to ground.
Maybe get an AE86 dash as they have the speed sensor built into the back of the speedo to give the speed signal to the good old Blue Top computer.
This worked fine when I put my gen3 3sge into my factory 4age Carina (AA63, factory 4age, T50).
Otherwise setup a reed switch and magnet on the driveshaft or the axle somewhere.

Ken
Ham
021 408 863

[johntramp]

Maybe get an AE86 dash

if only it was that easy... those sort of things dont exist these days

So if the ECU supplies the power, then should there be a +12v output from the SP1 pin? (I would check this but the wiring is not in the car at the moment)

Does the bluetop ECU need a speed sensor? As my car origionally had a bluetop when I bought it maybe there is something there already to solve this problem.

I will pull the dash out and see what I can find. If anyone is able to confirm how the SP1 pin works it will be appreciated.

Thanks

[matt dunn]

Cheers.

I see you have a similar engine. Did you use the unit inline with the cable in your Corolla?

Is there any benefit for the ECU to have an accurate reading?

No I dont run one. I dont even run a speedo or have a cable.
I run a Linkplus so no need.

They are not a full 12V pulse. Not 100% sure but wmay be 5 or 10v coming out.
Yes the dash has a reed sw in it and just pulses it to earth.
If your car was originaly a 4age it will have the sensor in the dash.

Matt

[johntramp]

The car is factory 3au but someone before me put a 4age in... and I have replaced that with a 20v.

Cheers for your help. I will see what I can do now.

Thanks

[johntramp]

is the speedo cable out of the gearbox 1:1 with the driveshaft?

[matt dunn]

is the speedo cable out of the gearbox 1:1 with the driveshaft?

No, and there are different ones available by changing the speedo drive.

If you pull the dash apart, on the face of the speedo on a part that is usually covered by the face plate there may be the words REV=xxxx.

The xxxx is pulses per km.

[johntramp]

I have an ae85 dash which doesn't have the speed signal. Approx how many pulses are there usually? I just want to trick the ecu into thinking I am driving so there isn't that early rev limit.

[matt dunn]

I have an ae85 dash which doesn't have the speed signal. Approx how many pulses are there usually? I just want to trick the ecu into thinking I am driving so there isn't that early rev limit.

Normally 4 pulses per revolution of the speedo cable,

but any amount will do to make it run properly as long as it does not reach the 180 cut out.

[johntramp]

is there any chance that just putting that wire to ground will be enough? or does it need some pulse

[matt dunn]

no, some form of pulse is required for the computer to see it as movement.

[johntramp]

ok. You dont have any cheap and easy ideas on how to do this? At the moment I am looking at using a 555 timer.

[maxium]

hey matt wot afftect will running no speedo sesnor have on the ecu operation?
a freind has a 20vblacktop in a escort race car and is having a few issues getting it to run right

[johntramp]

it has a lower rev limit and brings up a warning light

[slighty_sykotic]

hey matt wot afftect will running no speedo sesnor have on the ecu operation?
a freind has a 20vblacktop in a escort race car and is having a few issues getting it to run right

it has a lower rev limit and brings up a warning light

No, its farrrrr worse than that.

It wont run smoothly (at least with a auto ae111 blacktop ecu).

I had this problem in my aw11 with a blacktop.

Massive hesitation, feels like its missing really really bad.

Fixed instantly when I hooked up the wire.
--Sykotic

[maxium]

could we use part of the speedo cluster and hide it up under the dash in the escort just to use it for the speed sensor? would a ae111 be the best sensor to use??

[matt dunn]

I can supply electronic speed sensors that will screw in between the cable and the box and give you a 4 pulse signal.

Downside is i think they are about $180.
Will have to check that though.

Matt