Speed Sensor

[Pat Ford]

On Mon, 1 Mar 1999 Jason_Leone at amat.com wrote:

> Date: Mon, 1 Mar 1999 09:01:11 -0800
> From: Jason_Leone at amat.com
> To: diy_efi at esl.eng.ohio-state.edu
> Cc: Benjamin Marsh <bmarsh at turing.une.edu.au>
> Subject: Re: Speed Sensor 
> 
> <<The L-jet in my Soob is giving a fault code 33 which corresponds to
> a speed sensor in the workshop manual - I have pulled the dash out to
> try and find it. The closest thing I can find is a 3" long plastic
> strip with metal tabs at each end and a thing in the middle that kinda
> looks like a high voltage light bulb. Is this the speed sensor? ii so
> will just replacing it fix the problem or is the speed sensor somewhere
> else that I haven't looked.>>
> 
> There are three different types of "speed sensors" on most Euro cars. One is the
> Vehicle Speed Sensor (VSS), which is usually mounted to the tranny on FWD cars
> (and sends pulsed signals to the ECU). This one is used for speedo readings, and
> eliminates the need for a speedo cable. I doubt you car uses this!

on subarus the vss is on the back of the speedometer ( even on the gl-10 
digital dash)

> 
> The second type is the individual wheel speed sensor used on ABS equipped
> vehicles. composed of a gapped wheel (or race) and a magnetic pick up. Every
> wheel has this combo, if 4 channel ABS is present. Probably not applicable to
> your car...

not on 87 sub's


> The third type often used is the engine speed sensor. This measures the engine
> rpm (and can determine the angular timing of the crank, or position). Most are
> composed of a 60 toothed wheel bolted to the crank, and a magnetic pick up
> (sometimes an optical one is used). E30 model BMWs had a factory toothed crank
> wheel/crank pulley that was outside the block. Late model VWs have an internal
> toothed wheel bolted to the crank, inside of the block (flywheel end). VWs
> happen to read TDC off of the trailing edge of the 13th tooth, other cars are
> similar. This rpm signal goes to the ECU, get's processed...then the ECU sends a
> different signal to the instrument cluster (Tachometer).

this sensor is in the distributor, try removing the dist cap and check 
the radial play on the dist. shaft. I think the dist on the 87 4x4 and turbos
was an optical interrupter if it is clean it out w/ brake cleaner and 
compressed air.

> 
> The engine speed sensor will be in the engine bay. If it's an internal crank
> wheel, the sensor will be mounted into the block and will look like a knock
> sensor...but will be mounted much lower in the block. If you have an external
> crank wheel, it will be plainly visible off to the side of the crank pulley.

it's in the dist

> 
> However, the L-Jetronic system might not have what I'm talking about. I'd have
> to thumb through my Bosch FI book to figure that out. It's been awhile since I
> owned one of those cars. =)
> 

from 84 to 90 I was a mechanic at a Subaru, Saab, bmw dealership in Kingston
( di you know bmw stands for broken motor works)

> <<Car is a 1987 Leone RX Turbo>>

the rx's were fun I wish I had one 8-(

> 
> He he. Tell me more about this "Leone" car. Good name, I must say.
> 

in Canada this was just called a subaru ( it was around this time the 
second model line was brought into canada ((the justy))) 

> Jason
> '93 SLC
> 
> 
> 

Pat Ford                           email: pford at qnx.com
QNX Software Systems, Ltd.           WWW: http://www.qnx.com
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