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jbrasch 11-07-2013 05:56 PM

2005 l300 occasionally does not start
I have a L300, 2005, with 106,000 miles....lately it has been having a difficult time starting. It turns over, but does not start. New battery, connection good, changed spark plugs, new timing belt...mechanic thinks it is the BCM.
diagnosis code P1632 when car was not starting. code in BCM B0936, B2958, B1327, B3109, B2575, B2585. Getting tired of spending money.....

Any suggestions/thoughts would be appreciated.
Thank you,

fdryer 11-07-2013 07:20 PM

Re: 2005 l300 occasionally does not start
Is security flashing while starting? Security must be OFF while starting. A flashing security indicator during starting means GM's Passlock disabled injector operation as a theft deterrent. Security OFF while starting means an EFI system problem, not bcm. Passlock is part of many functions the bcm has.

Two things to check, fuel and spark. Air is assumed being ingested while starting to make the recipe work - a running engine. You may have to check fuses.

Fuel is the easiest to test for since a fuel test valve is within reach on top of the engine, "T" fitted onto the stainless lines. Turn on ignition, listen for the faint hum/hiss sounds of the fuel pump running for 2 seconds. Locate the fuel test valve covered with a large black plastic cap, remove cap to reveal the schrader valve, cover loosely with a rag while depressing the valve stem expecting a fuel spray. Cycling the fuel pump can only work if you wait at least 15 seconds with ignition OFF before trying again. A built in timer prevents cycling the pump excessively. (on the other hand, the pump is running when the engine's running) There's a fuel pump and injector fuse. If fuel sprays out then fuel and pressure are available to the injectors. Power to the injectors are a separate fuse. Spark is next.

Spark is the entire ignition system operating correctly and most difficult to test because of inaccessibility to plugs without plug wires. A different approach is needed to test for spark for L300's, indirectly. The indirect test actually tests for an intermittent or failed crank position sensor (CPS). A spark test on other Saturns with plugs and plug wires is easy to perform but not our L300's. A leap of faith is needed to test for a failed cps requiring removal - its next to the oil filter canister, mounted with one bolt. A resistance measurement with a multimeter should display 700-1200 ohms at room temperature, after immersing in boiling water or when rapped a few times against a table; heat,cold, and vibration are the environment cps' operate in. Any reading other than specified means a faulty crank sensor.

The cps supplies precise timing signals that the ecm needs in order to operate; the fuel pump, ignition system for spark, and pulse injectors. No cps output = no pump (while starting), no spark, and no injector pulses, a dead engine. With L300's, you can burn out the starter and battery but the engine will never fire up with a faulty cps.

fdryer 11-07-2013 08:03 PM

Re: 2005 l300 occasionally does not start
P1632 doesn't seem to be a valid error code. What does it point to? All other B-codes point to the bcm. Usually, bcm issues are announced with all the bells and whistles randomly turning on and off, instrument gauges/lights flashing, etc.. Posts by members described this as a car that's possessed. Worse case failure of the bcm - security is enabled permanently, disabling the engine from running, requiring a tow to GM to replace the bcm. Used bcm's can be 'married' to the car with a 30 minute relearn procedure posted here several times, retain mileage and cannot be altered. Remotes have to be programmed by GM.

s3nfo 11-08-2013 09:11 AM

Re: 2005 l300 occasionally does not start
P1632 from my Auterra Scantool GM specific code library "Theft Deterrent Fuel Disable Signal Received". You might try the Passlock Relearn proceedure and see if that fixes it. With the theft deterent code and all the B codes, your mechanic may be on to something.

fdryer 11-08-2013 11:26 AM

Re: 2005 l300 occasionally does not start
^ Good info. ^

If the security indicator is flashing during starting then Passlock is enabled and actively disabled the injectors to prevent the engine from running. The starter will crank the engine but no injector pulses just means the theft deterrent system is enabled. Either a 10 minute wait with ignition ON will reset Passlock for another restart attempt or the 30 minute Passlock relearn procedure is needed. For the 10 minute reset, leave ignition ON until security stops flashing, cycle the ignition switch OFF and try starting again - security should be OFF during starting.

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