Saturn L300 Intermittent Starting Issues

[mateo305ci]

Hello Saturn Fans!

This is my first post on here. I have "inherited" the job of working on my fiancee's 2001 Saturn L300 V6. It has just over 110,000 miles and has been pretty dependable up to this point.

In the past 2 months, the car has been experiencing several issues:
- Check engine light coming on with codes: P0601, U2105, & P1870
- Engine intermittently shifting rough. Sometimes after a hard shift, the "service" light w/ the wrench will appear.
- Sometimes, after a cold start, engine will run rough for 1-2 min before running smoothly.

Lately, the car has become more and more difficult to start. The engine will turn over, but will not start. Then, all the sudden, after several attempts, the car will start like there's no problem. This problem seems to be occurring more and more frequently.

So far I have:
1. Checked to verify that the fuel pump cycles on when the car is turned to ON.
2. Replaced the CPS (from what I've read on this board, it seems to be the culprit for these issues.

If anyone has any suggestions to fix this car or information regarding the trouble codes, it would be greatly appreciated!

Thanks!

[fdryer]

DTC P0601 Control Module Read Only Memory (ROM)

DTC P1870 Transmission Component Slipping

DTC U2105 Lost Comm with Engine Control System

The first and third lines most likely are due to the electronics having a spastic moment (it does happen) while P1870 is not good news. A reset of these codes are in order to see if they all come back. You can either use a reader to reset memory, pull the battery negative cable for a minute or pull the ecm B+ fuse for a minute. The battery cable wipes out radio memory while the ecm fuse only erases the ecm memory.

Are you aware that the car is due a new timing belt, water pump and spark plugs?

[mateo305ci]

I was not aware about the recommended replacement of the spark plugs, water pump, and timing belt. I'll work on getting them replaced proactively...thanks for the heads up!

My biggest concern right now is getting the car to start. Any suggestions? My plan tonight is to verify spark and fuel. What's the easiest way to verify spark and fuel on these cars?

Any other troubleshooting ideas/suggestions for the EFI on this car? I'm lost!

[fdryer]

Timing belt, water pump, spark plugs and fuel filter at 100,000 miles. There are no easy ways to check for spark as the ignition coil packs over each cylinder bank cover the plugs. Our ignition systems are termed coil-over-plugs. To even remove any plug requires back breaking work to remove the intake runners on each side, all the miscellaneous items hung on the back bank, disconnecting the oddball German stainless steel clamps, etc., before the ignition coil packs can be removed to see the spark plugs. Search the threads of members replacing the t-stat!? Its a given that as long as the engine runs, spark exists. The occasional crank position failure results in either a random engine die off or never starting up while cranking. Fuel pressure is simply checked at the schrader valve on the fuel rail. The test valve is capped to cover the tire valve.

Once the ignition is turned on, listen for the faint hum/hiss sound of the fuel pump running for 2-3 seconds. Then uncap the schrader valve and loosely cover it with a rag while simultaneously depressing the valve stem, expecting a healthy spray of fuel. You can use a fuel pressure gauge if needed; expect between 45-65psi.

Without any SES indication to read any error codes, you may as well try to have the 100k mile service done to see if this corrects any intermittent issues. There may be additional items to consider; the mass air flow sensor cleaning and possibly a transmission pressure control solenoid fault but that may be getting ahead too far. Search for past issues from other members with L300's.

[mateo305ci]

Thanks for the quick reply.

This evening I will run some diagnostics:
1. Pull the negative battery cable to reset the service codes.
2. Check any codes that come up after they've been cleared.
3. Check for fuel pressure at the schrader(sp?) valve.
4. Check for the security system light on startup(I've read that this can cut off fuel system)

If I don't find anything from these tests, I will replace spark plugs next.

I'll check back when it's all done.

Thanks again for the help!

[mateo305ci]

I tested the fuel pressure this evening as per the instructions by fdryer. Turned the key to the ON position, let the fuel pump cycle, and depressed the valve stem on the schrader valve located on the fuel rail. Nothing came out. No spray, no dribble...nothing. Am I doing something wrong, or does this indicate an issue with the fuel delivery system?

Thanks for the help!

P.S. I attached a pic of the schrader valve I checked. I wanted to make sure I'm checking the right valve.

[fdryer]

Yes, that is the fuel test valve (schrader valve). If you heard the fain hum/hiss of the fuel pump running for 2 seconds and stll no fuel spray from depressing the test valve, you can repeat cycling the ignition ON as many times as necessary (wait at least 30 seconds between ignition on cycles) to be sure the pump runs. Verifying the pump running and stll no fuel spray means; possibly a clogged fuel filter or gas cap possibly having a stuck vacuum valve.

Its not likely a faulty gas cap but you can always remove the cap and listen for any suction sounds and try the fuel test again. If the cap were faulty, removing the cap will relieve any vacuum in the tank immediately and should allow the pump to pressurize the fuel lines. It may take several ignition ON cycles to pressurize the fuel lines before fuel sprays out the valve.

To have the pump running as long as you want for this fuel pressure test without cycling the ignition on you can carefully use a jumper wire across the fuel pump relay socket pins 30 and 87 (after removing and famliarizing youself with the relay pin outs). This will send 12v immediately to the fuel pump and stay on. Be aware that you are deliberately wiring the fuel pump to run continuously without needing the ignition switch turned on. A wire jumper across the fuel pump relay and in the vicinity of the fuel test valve spraying fuel is a recipe for lighting a fire so be forewarned of this fire hazard and work safely. You are responsible for taking any action that can be hazardous. If you don't feel comfortable doing this then use a fuel pressure gauge that can be attached to the schrader valve without spraying any fuel while using a jumper wire across the fuel pump relay. This is much safer but you'll have to acquire the pressure gauge, possibly a loaner from Autozone (call to ask if one is available) otherwise you may have to buy one.

If you're mistaken and no fuel pump is heard running (have someone cycle the ignition while you press your ear against the car body near the fuel tank to listen for it) then you'll have to check the fuel pump fuse.

[mateo305ci]

I checked the fuel pump (listened for the noise) and it checked good. I switched out the FP relay, and checked the fuse. One thing I have noticed is that the car will only start when, with the key turned to the ON position, a whining noise comes from under the hood. No whining noise=no start. I have attached a picture of the part that the whining is coming from. What is this part? Could it be causing the intermittant starts?

Thanks!

[fdryer]

My apology for misspelling.

The fuel pump always runs when the ignition is turned ON for the first 2 seconds when you can hear the faint hum or hissing.

The picture you show above is the throttle actuator control module (TAC), the electronic throttle. The connector is above the electric motor that moves the throttle plate open/closed as well as sends feedback signals to the engine computer. It may whine but remains for the most part silent as it doesn't announce itself to let you know its working. It may be that the connector is loose or corroded and not making good electrical connections. The ignition switch should be OFF when disconnecting this wire harness to check the male/female pins/sockets for any corrosion. Usually, any electrical failure would automatically be detected to turn on the SES indicator.

You can check to see throttle plate movement by carefully removing the air intake tubing to see the throttle plate. This requires removing the mass air flow (MAF) sensor aside and leaving it connected. This is the round air tube just before the tac that measures air flow. With this aside and still connected electrically, you can observe the tac when turning the ignition ON and either have someone press the electronic pedal or wait 30 seconds as the electronics enters an automatic calibration for the tac; it will begin to move open and close very slightly to move the throttle plate to measure itself for closed position and slightly open. Someone sitting in the driver's seat can press the pedal for you to see throttle plate movement. Coordinate what you see against how far the pedal is pressed as a way to assess visual feedback of pedal travel against throttle plate travel. They should be moving together in complete synch since the pedal feeds signals to the ecm and the ecm controls throttle plate movement.

If the tac whines, this may indicate an issue that can mean something may be preventing the throttle plate from free movement and the motor is straining. This plate has a very strong return spring that can be over come by pressing hard with a finger or two to open it. It will spring back but its connected mechanically to the motor. Be sure the ignition is OFF before trying to physically open the throttle plate with fingers for inspection.

When you state that the fp checked good for noise, do you have fuel spraying from the test valve? Normally when the ignition is turned on, engine off, fuel pressure will be at 55 psi. This should readily spray out the test valve.

[mateo305ci]

I ended up taking the car to our mechanic. He spent three days doing diagnostics and tracing wires, and he has narrowed it down to the ECM or the BCM, and he is leaning strongly toward the BCM.

The problem is, the BCM supposedly can only be programmed by a dealer. Could a faulty BCM cause a no start condition?

[bluesl2]

Yes, it can. The passlock system goes through the bcm, if not working correctly, the fuel injectors won't work.

[s3nfo]

Something to keep in your back pocket, L BCM's are notoriously high failure items, L ECM rarely fail.

[mateo305ci]

Thanks for the info all. My gut is telling me its the BCM, is there any way to test BCM operation?

[fdryer]

Virtually all mini computers conduct their own self tests when applying power during every turn ON of the ignition key. When you see all the instrument panel lights turn on, its indicating a systematic preprogrammed procedure of self tests to ensure its ready for operation. The lamp test is done by the bcm as well as internal tests and if any wiring, electronic or program error occurs, an error code is automatically generated. No external test equipment is required. Past posts have consistently shown a cause and effect relationship that points to bcm failure before going to Saturn to confirm it. Only GM with their Tech II can properly diagnose a bcm failure as well as program a replacement. The only alternative is to buy a used one with their issues. Check posts about this.

In general, a bcm either works or begins to display failure characteristics ultimately failing altogether. Short of pulling the bcm fuses to force a hard reset, there isn't much to do.

[mateo305ci]

Thanks for the info. So as far as replacement of the BCM, is that strictly done by the dealer, or can one be programmed by the dealer and installed by the owner? Trying to keep the cost down!

Thanks!

[fdryer]

Unfortunately for us, only the dealer will perform all the work as an expensive electronic board that's susceptible to static discharge damage cannot be handled by anyone other than GM authorized techs to guarantee correct installation and carry a warranty from defect.

Used bcm's are for sale but mileage from the previous car cannot be changed.

[mateo305ci]

Hmm, is there any record of success on installing used BCM's? I'm leaning towards just sucking it up and taking it to a dealer, but I still don't like the fact that they charge so much for such little labor.

[uofmhighjumper]

First of all, I am not a mechanic. I simply have the same problem with my 2005 Saturn Ion. Had intermitant starting problems when we bought the car from a dealer last February. Had it in 3 x's within warranty period of 30 days for used vehicles. They could never replicate. With warm weather in MN the problem went away and came back in October. The dealer has had the car ever since (we have a loaner). They have tried putting in 2 used BCM's and neither of them worked. Now since the beginning of January they have had a new part 'on order'. There seems to be no new parts around. They have contacted Chevy (which I guess is taking over parts for Saturn) and they can't get anyone to manufacturer. They have 3 Saturns on their lot needing new BCM's. They can't give me a date to get the part since no one has committed to make it. If you have better luck, let me know. Lucky for us we have a loaner.

[fdryer]

mateo305ci, search through past threads for historical information. All bcm replacements done by Saturn are waranted and always work since Saturn stands behind their repairs for whatever the warranty calls for. Saturn members are glad their cars are back on the road.

Others that have bought used bcm's reported no issues once a relearn task is done to synch the replacement bcm (for security) to the car's electronics. Anyone going this route takes risks associated with third party sources.

I'm not convinced 100% that this is bcm related.

You never mentioned any security light flashing while starting. Does the security icon light up during the lamp test phase to indicate the bulb is in workng order? A dead bulb can be misleading if the security system is enabled; either from a fault within the bcm that may require a relearn to reset the bcm before considering replacing it.

[mateo305ci]

The security light bulb does work, as I have verified it's operation on startup. I think the plan is to take it down to a dealer tomorrow, suck it up, and have them run a diagnostic. I'll report back after that.

Thanks again everyone for your advice and expertise.