L Series Speed Sensor

Ben · Post by **Ben** » Wed Jun 28, 2006 7:51 pm

Can't get this speed sensor figured out!

attached wires to two likely looking spots on the back of the cluster

Both of the screws connect to metal on the inside of the speedo. Connecting between the wires and earth I am not getting any voltage or frequency coming off at any speed

Short of inventing a new speed sensor anyone get any quick fixes on this?

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Wed Jun 28, 2006 7:59 pm

If your dash isnt from an EFI L it wont have the speed sensor in the dash, the easiest way to get around it is to buy a reed switch and then glue a magnet to your tailshaft just behind the gearbox. If you wanna kill 2 birds with one stone you could buy a cruise control kit

SuBaRiNo · Post by **SuBaRiNo** » Wed Jun 28, 2006 8:34 pm

I heard it's better to put the magnets on the Inner CV joint and put the read sensor on the gearbox. I thought the balance of the tail shaft was rather important. I could be wrong.

I have it on the CV on my car... very easy to do and problem free.

Dave

subanator · Post by **subanator** » Thu Jun 29, 2006 12:36 am

See "Downloads" (above left link on this page) for EA82, Part 2, Section 2-7, look for Trouble code 33 - speed sensor, page 64 (PDF page 70).
Oddly this is for SPFI, as the MPFI trouble shooting guide is not included, but this sensor is common to both and should be ok.

It states it should output 2v moving slowly, and should be less than 10ohm to body.

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Thu Jun 29, 2006 8:40 pm

If you put the magnet right close to the joint itself it doesnt make much of a difference. I can still attain a very high speed with my RX without any ill effects.

wagonist · Post by **wagonist** » Fri Jun 30, 2006 7:04 pm

Suby Wan Kenobi wrote:If your dash isnt from an EFI L it wont have the speed sensor in the dash, the easiest way to get around it is to buy a reed switch and then glue a magnet to your tailshaft just behind the gearbox. If you wanna kill 2 birds with one stone you could buy a cruise control kit

Not true.
Every tacho equipped dash I've seen has one (just not connected to the circuit board) whether its carb or not.
You will find that you're non-tacho dash (I can tell by the circuit board) will not have it because non-tacho models were never available with EFI anywhere.

SCOOBIDOO · Post by **SCOOBIDOO** » Sat Jul 08, 2006 2:25 pm

MechaWagon wrote:Can't get this speed sensor figured out!

attached wires to two likely looking spots on the back of the cluster

Both of the screws connect to metal on the inside of the speedo. Connecting between the wires and earth I am not getting any voltage or frequency coming off at any speed

Short of inventing a new speed sensor anyone get any quick fixes on this?

right..one to earth and the other goes to nothing..THERE IS NO SENSOR THERE!!!!!!! I HAVE ONE THOUGH.

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Mon Jul 10, 2006 10:53 pm

If you didnt have a dash from an EFI equipt car you WONT have a speed sensor in the dash

jzk25 · Post by **jzk25** » Tue Jul 11, 2006 8:41 pm

Every L speedo I have looked at(too many) has had a signal generator in it. I have wired up my mates EJ25 L series speed sensor from the original 91 model non tacho non efi speedo head. I looked at dozens of others in the process and they all had signal generators regardless of age, tacho, efi whatever.
Originally I could not get any action out of it also and I ended up pulling a LS Efi cluster to bits and figuring it out from there. I found that the cluster needs 12v supply(not actually wired in IIRC), an earth at a specific point that isn't connected normally on a non efi and the signal to the ecu(the bolt you have connected too). The need for a 12v supply makes me think that it isn't a reed switch.

I can't be anymore specific unfortunately as it was a while ago and I try and avoid L series normally but I can say that it will work if wired correctly.

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Tue Jul 11, 2006 11:20 pm

I have only pulled an early tacho cluster apart and a later POVO cluster apart and did not find anything resembling a speed sensor.

Maybe the power is to unduce a magnetic field as opposed to using a magnet?

SCOOBIDOO · Post by **SCOOBIDOO** » Mon Jul 17, 2006 7:27 pm

jzk25 wrote:Every L speedo I have looked at(too many) has had a signal generator in it. I have wired up my mates EJ25 L series speed sensor from the original 91 model non tacho non efi speedo head. I looked at dozens of others in the process and they all had signal generators regardless of age, tacho, efi whatever.
Originally I could not get any action out of it also and I ended up pulling a LS Efi cluster to bits and figuring it out from there. I found that the cluster needs 12v supply(not actually wired in IIRC), an earth at a specific point that isn't connected normally on a non efi and the signal to the ecu(the bolt you have connected too). The need for a 12v supply makes me think that it isn't a reed switch.

I can't be anymore specific unfortunately as it was a while ago and I try and avoid L series normally but I can say that it will work if wired correctly.

you must not use crystal meth anylonger...no standard dash,s have speed sensor,s....the speed sensor is not a signal generater,it is a negative triggering reed switch which is actuated by a magnet on the speedometer bell,your just guessing at this stage, there is no 12v to this reed switch it is earthed, then send,s a square wave negative pulse to the ecu,which interpret,s it as a on / off signal....put a bucket under your chin for god sake...........

jzk25 · Post by **jzk25** » Mon Jul 17, 2006 9:01 pm

[quote=""SCOOBIDOO.[/quote"]
you must not use crystal meth anylonger...no standard dash,s have speed sensor,s....the speed sensor is not a signal generater,it is a negative triggering reed switch which is actuated by a magnet on the speedometer bell,your just guessing at this stage, there is no 12v to this reed switch it is earthed, then send,s a square wave negative pulse to the ecu,which interpret,s it as a on / off signal....put a bucket under your chin for god sake...........[/quote]

Thanks for your concise and informative post. Your insults are appreciated and they maintain the high standards you have set.

1. Standard L speedo heads do have a speed sensor. As mentioned in my post, I have tested and successfully wired one up to an EJ25 powered 91 Lseries. This is fact. I also tested many others and they too had speed sensors, also fact.

2. I know what a reed switch is and so does mechawagon and subi wan kenobi but thanks for the reminder.

3. I am not guessing about anything, except that you need to learn some manners when using internet forums.

SCOOBIDOO · Post by **SCOOBIDOO** » Tue Jul 18, 2006 8:16 pm

he does not know..he state,s this honestly.......dont forget to earth it all through your rear end......

jzk25 · Post by **jzk25** » Tue Jul 18, 2006 8:43 pm

Thanks for all your help, I hope your illiteracy problem clears up in time.

PeeJay · Post by **PeeJay** » Tue Jul 18, 2006 10:00 pm

I have had the innards of an L speed sensor sitting here in front of me for the last 3 years or so (lone time between clean ups).

It consists of 1 photo interrupter, 1 transistor, 7 resistors and one each of power, signal and zenner diodes. I've even got the schematic traced out somewhere.

I was in the process of designing a digital dash for my old MY wagon.

vincentvega · Post by **vincentvega** » Tue Jul 18, 2006 11:29 pm

know when to shut up scoobidoo. (that would be now)

Another fact for you. Al knows his shit. Theres no need for insults

wagonist · Post by **wagonist** » Wed Jul 19, 2006 9:07 am

Does anyone have a pic of where this output is on the non-tacho dash?
I went through this drama a couple of years ago when doing a conversion on a mate's car.
We ended up doing a tacho dash swap in the end to make sure because we couldn't figure it out.

jzk25 · Post by **jzk25** » Wed Jul 19, 2006 9:24 pm

PeeJay wrote:I have had the innards of an L speed sensor sitting here in front of me for the last 3 years or so (lone time between clean ups).

It consists of 1 photo interrupter, 1 transistor, 7 resistors and one each of power, signal and zenner diodes. I've even got the schematic traced out somewhere.

I was in the process of designing a digital dash for my old MY wagon.

Good info Peejay. From memory(as stated) I could not get the sensor to work without a power supply which is what led me to believe it wasn't a reed switch. I am not an expert on electronics(perhaps scooooooooobidooo can help as he obviously is) but I can say that I did get a speed sensor to work from a std no tach L dash. I also looked at and even smashed apart a few speedos in the process. I wish that I could do this again tomorrow to get the relevant info but I have changed jobs so this isn't possible.

Can any of you guys speculate on what specific type of sensor peejay's parts list would make?

VincentVega - Forgot to ask if you had the equipment to sniff the select monitor signals? I want to find the addresses for diagnostics and clear memory to (maybe) use in Impakts data monitor.

vincentvega · Post by **vincentvega** » Thu Jul 20, 2006 12:19 am

give me a schematic and I will tell you exactly whats going on (although by the sounds of it peejay knows a thing or 2 about electronics aswell..)

got that sch handy peejay? at a wild guess it sounds like an optical encoder (optical sensor counting revolutions of some part in the speedo) driving the transistor which switches low and provides the signal to the ECU.. like i said wild guess.

I will endeavour to have a setup ready to sniff the select monitor at your tech day Al. should be able to sort something out this weekend. It would be REALLY handy if i could get my hands on another select (or stereo loom) connector so i can make a loom up.. I need both ends, male and female.

PeeJay · Post by **PeeJay** » Thu Jul 20, 2006 7:17 pm

Yep, it's an optical encoder.

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