Faulty ECM in '94 850 Turbo?

detlef · Post by **detlef** » 16 Jan 2008, 15:54

New member here - came across the forum when looking for a reliable DTC listing.

I've been poking around the forum looking for a someone with a similar problem to no avail, so I hope it's ok that I'm starting a new topic.

I've been having some trouble starting my '94 850 Turbo with ~280k on the odo. I last drove it a week ago on a normal around-town trip, and this weekend when I went out to warm it up (the temps have dropped here in Wisconsin and my car lives on the street) I found it would crank, but won't start.

Some background. Normally when I turn the key to the II position I'll hear the fuel pump run for a few seconds. I replaced the original fuel pump at ~220k (late 2006) and the fuel pump relay less than 10k ago. The pump would run even with the original components in it, so this isn't a new behavior. I last replaced my plugs about 30k ago. All other maintenance has been of the routine/scheduled variety going back to when I bought the car with 194k on it (and immediately performed the 200k service).

I checked the diagnostics. In A1 I get 124 (Mode selector faulty or short circuit to ground) and 223 (Throttle position (TPS) sensor signal too low). In A2 I can't get a reading at all. The readout light actually glows faintly, and while it lights up when I press the button to activate the diagnostics, it won't display even a "No faults found" read.

Finally, when I was doing the diagnostics I noticed a strange clicking sound coming from the vicinity of the fuel pump relay. When I touched the relay I could actually feel a physical clicking occurring inside the unit. I swapped the relay out with a spare, and checked for the clicking again. Sure enough, it started again when I turned the key.

I've also checked the pertinent fuses - fuel pump, ECM, diagnostic unit - to see if any were blown or looked bad. Everything seems in order, though I couldn't say for sure since I don't have a multimeter.

About the only thing I haven't done is check to see if I'm getting spark at the coil by unplugging the wire, and that's simply because I don't have anyone to turn the key while I'm under the hood. My fianc

Post by **Ozark Lee** » 16 Jan 2008, 16:07

By virtue of the fact that you cannot interrogate the ECU I am suspicious of it.

Before you run out and buy a new one remove and clean both your positive and negative battery cables. If your secondary cables are not molded into the battery terminal and actually bolt onto the terminal remove and clean those connections as well.

...Lee

detlef · Post by **detlef** » 16 Jan 2008, 18:51

Thanks, Lee. I'm pretty suspicious of the ECM as well.

I give the terminals and connections a good cleaning every time I change the oil. I think my last oil change was about 1500 mi ago, and when I went out this evening I had a look. They're decently clean.

TODonnell · Post by **TODonnell** » 17 Jan 2008, 10:21

I had similar symtoms on my 94 850T w/ 175000 mi. Had fuel pressure but no spark. After a few parts changes with no sucess, I replaced the Cam Position Sensor and it started on the first crank. I would reserve the ECM until all the sensors check good.
Good luck,
Tim