993 Won't Start - DME Relay Already Replaced
 

Boys,

I've got no spark or fuel pump operation on my 1996 993 C2. The car turns over fine and other electronics are operating fine. What could be the cause of this failure ? I was thinking the DME itself although I'm not certain. Fuse 26(fuel pump) is not getting juice throughout starting process. Any diagnosis assistance would be appreciated. Thank you.

I'll bet it's your coils (I had the same problem last year). If no CEL, then 99.9% sure it's the coils.

Your fuel pump won't really kick on until your speed sensor detects a fast enough, sustained RPM. You can bridge terminal #30 and I think #87a on your DME relay plug to check your fuel pump. It'll bypass the DME signals and you can hear it whirr - to rule out that part.

Speed and reference sensors, drivers side to the rear of the motor (towards the front of the car)

white., black, and green connectors - make sure they are all connected.

AFJ

Genius Boys
 

The ODBII pulled an 0722 code which represents Speed Sensor Circuit not responding. Do you guys know the exact location of the Speed Sensor ? Thank you very much.

Rich

http://forums.pelicanparts.com/uploa...1146191640.jpg
Simple magnetic pickup, like an ABS sensor, reading your flywheel ring. Not much to go wrong - may have gunk on the business end or bad wire. On the 964, on pins 47 and 48 of the DME plug, it should read 3V AC (not DC) when you crank the starter - not sure if 993s use the same plugs.

Yes they do use the same plugs

usually, the coil in the sensor goes bad.