intermittent No crank and intermittent no start
hammer2
08-26-2016, 02:28 PM
2003 Grand Caravan with 3.8. suddenly had no crank condition. I moved relays around and still nothing. Battery tested and tested better than rated. removed start relay and "jumped" it and van cranked and started right up. Was able to drive home. Was thinking bad ignition switch or neutral safety switch (which grounds the start circuit via PCM when vehicle in neutral or park thus energizing relay and causing starter to crank). Figured I could use it by jumping rely when needed to go to work next day. Went out to go to work, jumped relay, engine cranked but NO life-not even any sputter. Seemed like no spark or fuel or both. As far as I know neutral safety switch is only part of start circuit, so if jumping relay (thereby by-passing start circuit) and engine cranking but not starting, I think neutral safety switch NOT the issue.
I played with things and put in park, then neutral, then various gears, and tried to start in all of them. Suddenly in neutral it started with key. But when changed gears it stalled and then no crank. Next day it started right up. let it run for a while and moved it. no problems. used key on/off to check codes and got 1684 battery power to module disconnected, 1282 fuel pump relay control circuit and 0171 lean bank 1. Shut it off and re-started it about 10 times in a row. Each time I could hear the fuel pump energize when turned key to run. Then suddenly I thought maybe I didn't hear it and when turned key no crank. played around with gear shift again and it eventually started. Since from above neutral safety switch would seem to be eliminated, this seems like strange behavior.
Of note, the ABS light is on now (it was not before this all started) and the "trac off" light is lit up when idling in park, which seems to be some malfunction and is also new. Pushing the traction off button has no effect on turning light on/off.
Given all of these strange issues, I am thinking PCM bad? or PCM ground bad? thoughts? How/where is PCM grounded?
I suppose ignition switch could be bad but I can't get wiring diagram. Best I could figure out with wires I can trace and by removing it and testing with continuity tester, it seems OK, but it could be intermittent. I am waiting for a no crank condition and then need to check for power at the starter relay when key turned to start . If I have power at the starter relay in the slot that is supposed to get hot when key is turned to start (slot 86), then the no crank is NOT due to the ignition switch. But the no start when jump starter relay and engine cranks but does not start still COULD be the ignition switch. But then that would mean that two things are bad. Which would seem unlikely for two two things to go bad at same time. add in the new lights on dash and hence feeling that PCM may be bad.
I played with things and put in park, then neutral, then various gears, and tried to start in all of them. Suddenly in neutral it started with key. But when changed gears it stalled and then no crank. Next day it started right up. let it run for a while and moved it. no problems. used key on/off to check codes and got 1684 battery power to module disconnected, 1282 fuel pump relay control circuit and 0171 lean bank 1. Shut it off and re-started it about 10 times in a row. Each time I could hear the fuel pump energize when turned key to run. Then suddenly I thought maybe I didn't hear it and when turned key no crank. played around with gear shift again and it eventually started. Since from above neutral safety switch would seem to be eliminated, this seems like strange behavior.
Of note, the ABS light is on now (it was not before this all started) and the "trac off" light is lit up when idling in park, which seems to be some malfunction and is also new. Pushing the traction off button has no effect on turning light on/off.
Given all of these strange issues, I am thinking PCM bad? or PCM ground bad? thoughts? How/where is PCM grounded?
I suppose ignition switch could be bad but I can't get wiring diagram. Best I could figure out with wires I can trace and by removing it and testing with continuity tester, it seems OK, but it could be intermittent. I am waiting for a no crank condition and then need to check for power at the starter relay when key turned to start . If I have power at the starter relay in the slot that is supposed to get hot when key is turned to start (slot 86), then the no crank is NOT due to the ignition switch. But the no start when jump starter relay and engine cranks but does not start still COULD be the ignition switch. But then that would mean that two things are bad. Which would seem unlikely for two two things to go bad at same time. add in the new lights on dash and hence feeling that PCM may be bad.
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