Porsche Enthusiasts Club Forum

My 944 has once again broken down, in exactly the same way as last time:
http://forums.tipec.net/viewtopic.php?f=25&t=16607

I think the problem this time is the other sensor, as I replaced the reference sensor last time.
The confusion is that when testing according to Clarks Garage I can only get a resistance reading across pins 25 and 26. Even the newer sensor does not give a reading across pins 25 and 78. I can also read a good 2.2V AC across pins 25 and 26 with the engine cranking.

This either means that the new sensor is dead already, or that those tests don't work or apply to my car?

However, I have deduced that I get no reading at all on the older sensor. But I don't know if the above means that both sensors are dead, or just the older one.

Help!

Try the sensor at the plug, should be around 980 Ohms from memory. It could possibly be the loom for the sensors which is intermittent.

if your near a maplins or similar build a little tester
from here http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/343212-hiow-test-crank-sensor.html

you can test by it flashing put on crank sensor end then put on pin end in cab that will show if wire is broken or sensor faulty
i keep it in the car at all times just so simple to test sensors as well as a noid light i built

Jim - I was testing these directly at the sensor plug.

Campervan - I put my multimeter on AC voltage and was able to read 2.2V when cranking over, which seems like the same test as the LED test you linked to, and the oscilloscope that Clarks mention.

hi althejazzman i am assuming your testing the speed sensor and gettin no ohms from it ?
pins 8-27
ref sensor 25=26
both should have around 600/1600ohms on at plug in engine bay but also check at dme in footwell to rule out wire from sensor
i got my sensors from gsf £37 quid at mo just looked online when i change mine but to honest after being off road for two months and changing sensors and sec hand
dme i think it was poss a broken wire somewhere
the beauty of the little light i built is it will flash with each pulse one for tdc sensor per revolution of engine and multiple for speed if your not in a rush poss build one as handy to have .

Try fastening a cable tie loosely around each wire on either side of the connector and then tying them together using a further pair of cable ties, after tightening up and trimming the 'collar' tie wraps. This will use eight cable ties in total and will keep the two connectors held together tightly.

It may end your problems.

Apparently I'm supposed to also get a reading across pins 25-78 on the reference sensor, and pins 8-23 on the speed sensor? Is this wrong?

if your going by clarks you are correct
http://www.clarks-garage.com/shop-manual/ign-02.htm
but i think the 1m ohm is the earth part as on my 944 loom side there frayed, sensors are new
i originally tested mine using youtube guide
http://www.youtube.com/watch?v=zeFOOcLSk60
however if you read my post
viewtopic.php?f=25&t=17069
you will see i change mine due to not realizing at time the tdc has one pulse per revolution and fault lying elseware ??