02 LW300 V6 Fuel Pump and OBD2 Trouble

[02LW300]

Originally Posted by 02 LW300

Good name, I will just hang out at the Saturn forum from now on.
Andy

Wow I was surprised to find that username available but didn’t think to put a space in there.

[02LW300]

Hey guys, this is LUXWAG. I was unable to post so I made a new username.

So here’s where I’m at today

-engine turns over, no start, service wrench light and service engine soon light, fuel gauge shows Empty, OBD2 scanner won’t link
-jumping fuel pump relay makes fuel pump work and I get 41 PSI fuel pressure at fuel rail test port but still doesn’t start/run
-spraying starting fluid in throttle body does not get car to start/run.
-battery is new and fully charged
-tried starting with ECT disconnected and doesn’t start/run
-security is off and doesn’t blink when starting

So I know
-Fuel pump works but only when bypassing relay
-not getting spark or fuel on startup
-OBD2 port won’t link to reader


Any ideas here? Are there any sensors going bad that would cause these symptoms? It’s like the ECM is preventing the ignition cycle?

[fdryer]

Fuel pressure fine, starting fluid fails to get the engine firing up suggests a spark issue except for one other problem that kills the entire EFI system if it doesn't operate, - the crank sensor. The ecm cannot run the EFI system (fuel pump, generate spark and pulse injectors) if the crank sensor failed. It's located next to the oil filter, mounted with one torx bolt. A three wire sensor. The connection is below the right side of the main intake manifold. If you have a digital multimeter, measure it for resistance. Two wires should measure between 700-1200 ohms. Its sole job is to detect crankshaft timing notches and generate a clock signal for the ecm. The ecm requires a crank sensor to run. When starting and engine running, the crank sensor continually outputs precise timing signals to allow the ecm to operate. One tell tale indicator would be a lack of engine rpm on the tach while starting. Approximately 250 rpm should be seen on the tach while starting.

[02LW300]

Well when I try to start the car, the tach doesn’t move at all.

I’m going to see if the auto parts store has the crank position sensor and swap it out.

[02LW300]

I pulled the crank position sensor and it has no resistance…could this be it?!!!

[02LW300]

Well I’m dumb…I didn’t test the correct way. It turns out the crank position sensor has 874 ohms. So that checks out, but why don’t I get any RPMs when I try to start?

What else should I look for?

[fdryer]

Is 874 ohms measured on the original crank sensor or new one? Please be specific as no one is standing next to you. If you measured resistance on the original one, rap it against a work bench a few times, a crude form of engine vibration then measure resistance. You might have to immerse it in boiling water and measure resistance again (as in engine heat).

[02LW300]

874 ohms was on original crank sensor.

[lrbraner]

Originally Posted by 02LW300

Well when I try to start the car, the tach doesn’t move at all.

I’m going to see if the auto parts store has the crank position sensor and swap it out.

My experience has been that if the crank position sensor is bad, the engine will not turn over. Will not do anything.

[02LW300]

Back to talking about the security light…

Is the security light (the yellow one that says SECURITY on dash) supposed to come on after turning key to RUN then shut off a few seconds later?

When cranking the engine, the security light does not flash.

[Rj 2000 LS2]

Don't rely on a ohm's test to determine crank position sensor is good or not. A bad one will simply not provide clocking to the ECM and therefore no start. The crank position sensor provides the clock to fire the spark plugs. It is a signal not the actual spark. Don't confuse the two.

I thought you sprayed started fluid in the intake and it fired? Or is that another thread? If it fired with starter fluid, it's got spark. However, a CPS can be intermittent if the end is covered in metal pieces. Make sure the crank position sensor is very clean when you install it.

if the code reader can not communicate with the key turned to RUN, perhaps the key switch is bad. Can you turn ON your radio with the key switch ON?

[Rj 2000 LS2]

Originally Posted by lrbraner

My experience has been that if the crank position sensor is bad, the engine will not turn over. Will not do anything.

The engine will rotate but will not start if the crank position sensor is bad. I am thinking the key switch is not really switching the RUN wire to ON, therefore gauges don't work and the ODBII device can not connect because nothing has power. This would also explain the no start issue. I really don't know how to test or diagnose the key switch functions. But, it makes sense why it is not working properly and all the other items are chasing tails.

There must be a method to test the key switch to determine if the power is switched ON to all modules.

[02LW300]

So I put a new crank position sensor in and it didn’t change anything.

I have a new BCM that is being programmed on Thursday so hopefully that solves the problem.

[fdryer]

Originally Posted by 02LW300

Back to talking about the security light…

Is the security light (the yellow one that says SECURITY on dash) supposed to come on after turning key to RUN then shut off a few seconds later?

When cranking the engine, the security light does not flash.

Yes, security is the yellow indicator. Apparently, L300s like mine, have car symbol with a large padlock at the 6'oclock position in the tach.

When turning on ignition, GMs Passlock always performs a security check, starting with the sensors detecting turning the ignition switch, sending signals to the bcm. When the bcm senses the correct signals, it sends a fuel password to the ecm to allow injector operation and turns off security whether starting or not. If an incorrect signal is detected then the bcm sends a different password to the ecm. The ecm then disables injector operation. Security with turn on them turn off during starting. All indicators are turned on as part of lamp tests then turn off at ignition on time before or during starting. The battery, oil and seat belt indicators are left on until the engine's started. Seat belt light turns off when buckling in.

With security indicator off while starting, Passlock (bcm controlled) is disabled, not interfering with ecm/EFI operation. With 874 ohms on the original crank sensor, it's fine.

Has anyone made repairs to this engine? Engine ground, between battery negative to chassis then chassis to engine block may need to be checked. The ecm should be that square 5" x 5" thing sitting on driver's side of the engine with two large multiple pin connectors. The ecm is grounded by mounting bolts to the engine. One member dime years ago had problems starting until he mentioned his ecm was loosely mounted with one bolt and not secured. Once this was mentioned, replacing the missing bolts to securely mount the ecm to engine block made all his problems disappear.

Worse case scenario would be removing upper intake manifold system to remove the front ignition coil pack and spark plugs, examining plugs soaked in fuel (or not), reconnecting plugs to ignition coil pack, coil pack reconnected to wiring and plug bases wired to engine block. Have someone start while you observe for spark on all the 3 plugs to verify spark occurring.

[lrbraner]

Originally Posted by Rj 2000 LS2

The engine will rotate but will not start if the crank position sensor is bad. I am thinking the key switch is not really switching the RUN wire to ON, therefore gauges don't work and the ODBII device can not connect because nothing has power. This would also explain the no start issue. I really don't know how to test or diagnose the key switch functions. But, it makes sense why it is not working properly and all the other items are chasing tails.

There must be a method to test the key switch to determine if the power is switched ON to all modules.

That has not been my experience.

[02LW300]

There has been no repairs made to engine. I’ll have to check the engine ground and see how it looks. The ECM has all four bolts and they are tight.

I think I’ll test the coil pack for spark and see what happens.

I’m having the car towed to a GM dealer to get a new BCM programmed on Thursday.

[02LW300]

I was looking at the starting and charging system electrical diagram and noticed that there is a red wire coming from the alternator to the ECM. I’m assuming that this is how the ecm gets power? And would a bad alternator mess with the ecm?

I’m going to check the wires on the alternator tonight and see what they look like.

[fdryer]

GM service manual diagrams show two red wires; a fusible link wire and a signal wire from the ecm. The ecm (red) wire is not power. It's a turn on signal from the ecm to command the alternator to generate power.

When ignition switch is turned on, this wire is grounded internally in the regulator circuit telling the ecm to send a low battery signal to the bcm to turn on the battery light. When the engine's running, the solid state regulator opens this circuit, turning off the battery light. This red wire does not power the alternator.

The fusible link wire powers the alternator at all times (HOT), coming from the starter terminal where battery (red) is connected. The alternator's solid state regulator determines when to initiate output.

[Rj 2000 LS2]

Originally Posted by lrbraner

That has not been my experience.

A defective CPS can't disable to the starter from spinning the engine. The CPS strictly is a signal generator to provide clocking signals used to time the engine. It's the chicken and the egg theory, no spin means no clocking and no start.

Hey, that makes me think... perhaps the timing belt is broken? What does the engine sound like while rotating during attempted start?

[02LW300]

Originally Posted by Rj 2000 LS2

A defective CPS can't disable to the starter from spinning the engine. The CPS strictly is a signal generator to provide clocking signals used to time the engine. It's the chicken and the egg theory, no spin means no clocking and no start.

Hey, that makes me think... perhaps the timing belt is broken? What does the engine sound like while rotating during attempted start?

It sounds like it should, but how would I check the timing belt? Do I have to take the cover all the way off?

What would a broken timing belt sound like?