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Sometimes no start, Most of the time start

766 views 3 replies 2 participants last post by  djtho1 
#1 ·
I have a 2002 E350 with the 7.3. A couple of times now it has decided not to start. Cranks fine, but won't start. Then, after awhile it starts fine and we move on. Tonight I was messing with my new obdII scanning program (OBD Fusion, still trying to figure it out), and the issue happened. When it happened, the PCM dropped and all obdII communication ceased. A couple of minutes later, after cycling the ignition a few times, my communication came back and it started fine. I also get the "service engine soon" light and sometimes a couple of other dash lights will flash.
So, a couple of questions. My batteries are a bit low at 11.1 volts. I know the PCM can be picky about exact voltage. Could this be the cause?
Or, is the PCM dying? Unfortunately, this might be a job for the Ford dealer.
 
#2 ·
I can get it to replicate the issue fairly regularly now. Even with a battery charger connected I am only showing 11.1 volts at the PCM (according to the obd II port). Once it starts I show 13.4 or so, which is about normal. Could all this be caused by a bad PCM Relay or a bad auxiliary battery?
 
#3 ·
This morning I isolated the batteries. One battery shows 12.5 volts and the other battery shows 12.7 volts. With one battery connected the OBD II monitor shows 10.1 volts. With both batteries connected it shows 11.2 volts. Why would this voltage be so low?
 
#4 ·
I think I have isolated as much as I can and there doesn't seem to be any support here, so it's off to Ford. The van has an appt Thursday.
 
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