No start, issue between DME and Main relay? (solved)

[Komzorz]

Last Sunday my car decided to not start in my driveway, trying to figure it out. When I turn the key on, neither of the fuel pumps make any sound, but I can bypass the fuel pump relay to turn them on and the car still won't start. From the exhaust smell (or lack thereof), seems like the injectors aren't firing, even when the fuel pumps are confirmed operating.

So, I did jlevie's diagnosis thing and got to step 3:

Troubleshooting:

Disconnect the battery and the DME cable. Then:

1) Disconnect the coil negative and check continuity from that connector to DME pin 1. Also verify that from DME pin 1 to ground is an open circuit.

All good here.

2) Check the resistance across DME 47 & 48, which should be 500-560 ohms. If the CPS is dismounted, the resistance can be seen to change from about 500 to 540-560 when a ferrous object is brought to the face of the sensor. Neither pin should be grounded.

Right in the 500-560 range.

3) Check for continuity from DME 36 to main relay 85 and from DME 3 to fuel pump relay 85.

Not getting any continuity from DME 36 to main relay 85.

What does this mean? I have a random break somewhere in the harness? Any help would be mucho appreciated.

[jlevie]

That is what it sounds like. Does the main relay close when the ignition is turned on?

The fuel pumps are only on when the DME sees timing data from a rotating engine. They should not may any sound with ignition is switched on.

[Komzorz]

Turns out the end of my crank position sensor was so grimy it was preventing it from working.

Note to self: physically go and check out all suspected components for condition. I suspected the CPS the whole time from how it was acting, but reading the correct resistance threw me off.

Obviously, it must have been accumulating grime from the minor oil leak I've been totally ignoring for quite some time now.