jns

I just installed two new ref/speed sensors and the car wouldn't start. The tach wouldn't jump so I checked the sensors and have .973k ohms at the two side-by-side contacts but have zero(meter shows "O.L") at the outer contacts where there should be >1 megaohms according to Clark's Garage. These are new sensors from Autohaus AZ. Even if my meter was wrong and the sensors are ok, I should have a bouncing needle at the tach while starting.WTF?

J Chen

Is your clearance correct ?
Wrong connection between
the two sensors will also
cause a no start situation.

Tom M'Guinn

Also, make sure you did not swap the connectors when installing.

Lorenfb

The best way to check the speed and ref sensors is at the DME connector.

1. check the speed sensor between pins 8 & 27
a. resistsnce - about 1000 ohms
b. A.C. volts - between 1.0-2.0 VAC when cranking

2. check the ref sensor between pins 25 & 26
a. resistance - about 1000 ohms
b. A.C. volts - about .10 VAC when cranking

As Tom says, make sure that the connectors didn't get switched, a common problem.

mark944turbo

I dont think the clearance will be the issue, the signal that gets generated is huge. Unless you installed them too close, and the spinning flywheel and starter ring destroyed them. I once did this and had think copper wire wrapped around and around 20 times. It wasnt fun to get out.

Lorenfb

"I dont think the clearance will be the issue, the signal that gets generated is huge"

Mark is correct. The position of the sensors is not that critical. Actually, I've started
944 engines just "waving" the ref sensor near a bolt or metal engine part.