Won't crank + can't link to PCM

[lgmagone]

My car refused to crank. Worked fine to drive to work, now can't drive it home.

PATS link blinks once every 2 or 3 seconds when key is off and during start process.

Tried to link using my Equus 3150 code reader to see any codes in system. Can't link to vehicle PCM. Prior to yesterday, worked fine.

Have tried multiple keys.

Looks to me like a bad PCM? Any other thoughts?

If the halo is bad for the PATS, would it blink faster or go steady?

 

[matt0248]

A PATS failure would not affect the ability to connect to the PCM.

 

[adambant]

When you turn the key to RUN, does the check engine light illuminate? Also check your fuses.

 

[lgmagone]

All of the dash lights work like normal (check engine + all of the others).

 

[matt0248]

If the CEL comes on than the PCM is not completely dead.

 

[lgmagone]

Update: Fuse #41 is blown. It powers the PCM, oxygen sensors, vmv, among other things. Reading online, most likely short in harness somewhere. Will fstart troubleshooting once I can get a copy of the vehicle wire diagrams.

 

[matt0248]

Update: Fuse #41 is blown. It powers the PCM, oxygen sensors, vmv, among other things. Reading online, most likely short in harness somewhere. Will fstart troubleshooting once I can get a copy of the vehicle wire diagrams.

Check the O2 sensor wiring, It can sometimes rub on top of the transmission, also the heater element in the OX can sometimes short out causing a similar issue.

 

[lgmagone]

Solved!

Looked underneath car at O2 sensor wiring. Found the wire harness fell out of the plastic clip that is supposed to keep it secure, and the pigtail to the O2 sensor was lying on top of the driveshaft. One wire had the insulation worn clear down to the bare metal, and this was likely the power cable to the heater. Putting electrical tape on it and replacing the blown fuse will allow me to get the car home tonight until I can decide what to do for a permenant repair.

So, the short in the heater power cable of the O2 sensor blew the fuse, which also provided power to the Powertrain Control Module. With no power, the PCM wouldn't allow the starter to crank. Took many hours to diagnose, but only about 10 seconds to fix.

Fortunately, it died in the company parking lot and I had a few days to research it. Glad I didn't have to have it towed.

 

[Jimmy4765]

Had the same problem on my 02 XLS. Was going to pull the PCM and go order a new one from the parts store. Decided Id just look around a little and found this and it fixed me right up! Thanks guys!

 

[Cubanlorenzo]

Same problem in my 2003 flex. I was in a parking lot and my car stalled. Went to start it and got nothing. No crank, no click, nothing. Initially I checked relays and then thought starter. Pulled the starter (which was a breeze) Went to Advance Auto and hot my starter checked. It was fine. Came home and put that search button to use. Came across this thread. My o2 sensor wire had too been frayed by my driveshaft and caused a short blowing fuse 41.
Just wanted to say thanks, saved me time and money

 

[mike6348]

Same issue. Started to take off for a green light and died the minute it started moving. Fortunately I was not in the middle of the intersection yet but it died in a really bad spot. Putting on flashers and sitting in the car is no help for the clueless who sit behind me a keep honking. So I got out to call AAA - going to be 40 minutes. I really don't want to keep sitting outside in 10 degree air in blowing snow so start to go sit back in the car and listen to people honk when the sheriff shows up pushes me through the intersection to a safer spot. I had the tow truck drop it off in the driveway and got the "why didn't you have them take it somewhere to get it fixed" from the wife. My exact words were "I'll look it up on the forum - somebody else has probably had the same issue"

Yep.

Went out this morning and found the fuse blown with the harness for the drivers side rear O2 sensor sitting on the front driveshaft with the insulation worn off one of the wires. Replaced the O2 sensor and tied up the harness.