2000 5.4L turns over but will not start
#1
2000 5.4L turns over but will not start
I have a 2004 5.4L that worked fine one day, but would not start the next. It turns over and is very close to starting, but won't catch. I have done some basic diagnostics to make sure the battery is good, the fuel pump is working, and that it is getting an ignition signal at the COP. I have checked all of the fuses and relays to make sure they look good. The only thing that does not check out according to the manual I have is that I get no voltage at the Camshaft position sensor, or the crankshaft position sensor with the ignition on. The manual says I am supposed to see battery voltage. This makes me think it is the PCM. Does anyone have any ideas?
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#6
Join Date: Dec 1997
Location: Windsor,Ontario,Canada
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Disconnect the PCM and the Crankshaft position sensor. Measure the resistance of the Crankshaft position sensor positive circuit and negative circuit. It should be less than 5 ohms. If not the circuit is open. If that checks out let me know and I will send you the complete test procedure.
Regards
Jean Marc Chartier
Regards
Jean Marc Chartier
Last edited by JMC; 12-09-2004 at 10:08 AM.
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#8
Join Date: Oct 2002
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Oh! A 2000! That's diffferent. See if this helps.
Check for battery voltage (ign switch to RUN) at the RED wire at the MAF. If missing, check fuse F18 in the underhood fusebox (15A).
In addition to the MAF, F18 supplies the PCM, fuel pump relay, fuel injectors, and IAC. The cam and crank sensors are supplied from within the PCM, possibly from this same 12V line. The EVTM does not give that detail.
Steve
Check for battery voltage (ign switch to RUN) at the RED wire at the MAF. If missing, check fuse F18 in the underhood fusebox (15A).
In addition to the MAF, F18 supplies the PCM, fuel pump relay, fuel injectors, and IAC. The cam and crank sensors are supplied from within the PCM, possibly from this same 12V line. The EVTM does not give that detail.
Steve
#9
I checked the #18 fuse to make sure it was ok. I even replaced it with another to be absolutely sure. No problems there.
I have not measured the resistance of any of the circuits connecting the sensors to the PCM. Since the power problems are occuring on several of the sensors, I didn't think it was an open circuit. I will check that this weekend though.
Thanks for the ideas, please keep them coming, I'm sure one of them will identify the problem.
Scott
I have not measured the resistance of any of the circuits connecting the sensors to the PCM. Since the power problems are occuring on several of the sensors, I didn't think it was an open circuit. I will check that this weekend though.
Thanks for the ideas, please keep them coming, I'm sure one of them will identify the problem.
Scott
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If you are missing voltage where there should be voltage, then obviously you have an open circuit between that point and the source...
Make the voltage check first before spending time "shotgun" testing sensors. If there is no power to the sensors or the PCM on the correct feed, then the system won't operate.
Steve
Make the voltage check first before spending time "shotgun" testing sensors. If there is no power to the sensors or the PCM on the correct feed, then the system won't operate.
Steve
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#12
you might want to start by checking all fuses in the box under the hood on the drivers side ther are many fuses related to the computer and engine managment system, also in that box are relays, fuel pump, computer power etc. get yore owners manuel and star checkin fuses and relays coomon to the engine system.
#15