2003 22v Wont Start or Turn over

[LIL RED]

I've had my 2003 22v (6.0 GM LS Engine) for about 3 year now with no issues and know will not start or turn over. I tried to start it for the first time in about 2 mouths this weekend to find out it will not do anything even after bypassing the neutral safety switch. I have power to all gauge but my RPM gauge is constantly beep with no display. Could I have a bad RPM gauge does it have to communicate with the ECU to fire up. The only way I can get the starter to turn over but engine still doesn't fire up is to run a wire from the ignition side of the neutral safety switch to the starter wire.

Any info on this issue after 4 hours of checking voltage and wiring I can find any issues.

[UNSTUCK]

What’s happening at your key switch? With the key in the crank (start) position you should have at least three wires with power. One is power to the switch. One is power to the starter circuit and the third is power to the ignition circuit. You may also have an accessory wire that’s hot, but you may also notice that it turns off in the crank position.

It seems funny to me that your gauges come on. That tells me the ignition circuit is getting power, but if that’s the case running a jumper to the starter should have made it start and run. When you ran that jumper you likely bypassed a starter relay. That relay prevents starter solinoid amps from going through the key switch and neutral safety switch. Check that you have both ignition and switched power at that relay while craning the motor. Remove your jumper wire first though so it doesn’t really crank.

[freeheel4life]

^^ all good ideas. A great quick way to diagnose key switch is turn it to IGN position. If you don't hear your fuel pumps run for a couple seconds to prime then engine ECM isn't getting voltage from IGN wire (should be purple wire). Once you've confirmed ECM is getting voltage from purple wire it's time to make sure yellow wire with red stripe is getting voltage from key back to starter relay. If you have that and still not start then it could be starter relay.
If you verify you have good voltage at the ignition switch and nothing is happening behind you I would start by checking the plug at the engine harness.
The other obvious one after boat has been stored is checking battery voltage, and connections if batteries were pulled out and tended. Missing 1 ground can make all the difference
Don't forget the deadman switch if boat is equipped with one as well. Usually boat will start for a second then will die if that's the case tho...jusy thinking of the variables.

[Brianrzr]

Big question is what happened since the last time it ran? This time of year mice are a real possibility. Little sob’s can get anywhere. Might be as simple as a chewed wire.

[LIL RED]

Thanks guys I'll run thru a few other test today. I do have starter voltage in full start position. This voltage is getting to the nuetral safety switch but not 100% sure it going all the way to the ECU.
The fuel pump does come on to pressure the rails and or injectors but just will not turn over. I also pulled the plugs and no gas on them bone dry so that tells my the injectors are not firing either. I'm pretty sure I'm not getting park either.
It stored in my shop at my house and don't think rats are the issue because I don't see any wire anywhere that show chewing.

I'll update once I check a few other point but I don't remember the RPM gauge with constant tone is this normal. If so I assume it's oil pressure but don't know because my digital read out is blank.

[freeheel4life]

Is this a Merc or Marine Power engine??

[LIL RED]

This is marine power set up

[freeheel4life]

So there's a slight chance with the buzzer on all the time that the TAC module is limiting spark or fuel due to error codes, but you would need Diacom to confirm. We had a boat in a while back that had this problem, but it would start and run...it just would lope on its own then die shortly after. Also had zero throttle as it was DBW.
Ended up being a voltage issue. The module get a upset if it sees different voltages at engine vs helm.
Problem ended up being at the large flip type breaker just past the battery. Had a voltage drop due to resistance internally.
Not sure if this is your problem, just throwing out ideas as it was ringing the alarm constantly at dash as well...it wasn't the 6.0 though. Was the MP 5.7 configured as the 340hp

[KoolAid]

Key "on" works, which is giving power to the gauges and pretty much everything else. Engine won't crank which sounds like a bad fuse on the yellow with red striped wire from the ignition. Then when bypassing the switches the system will crank but will not start. That sounds to me like the ECM is not powered up. '02 with a marine power engine would have been a pretty rare sight. I think there was a thin red wire on the port side that went directly to the battery switch which powered the ecm. Look for that wire and be sure its connected/has power.

[LIL RED]

thanks ill look into this breaker today. I did check all my voltage at the almost ever place I can think of but need to check the breaker that's mounted behind the ECU Plate. ill keep you in the loop and thanks.

[LIL RED]

I've checked the voltage on the yellow and red wire at the ignition switch (12.85) at the neutral safety switch from the ignition switch (12.80) on the other side of the neutral safety (12.80). I guessing this side of the neutral safety runs to the ECU because I'm not getting the voltage at the starter solenoid. The only way I can get the engine to crank over is to jump a wire from the ignition side of the neutral safety to the starter solenoid.
Other issues I noticed last night was the fuel pump come on to pressure the system and about 10-15 seconds it will turn on again but this is very random. this is just fuel pressure and know the injectors are not firing because there is not fuel in the plugs bone dry.
I'm going to check this red wire that is terminated at my battery switch that runs into the harness where the yellow/Red ignition wire is going.
I'm going to pull everything apart tonight and make sure all connections and plugs are terminated good and have voltage were I know I should have it.
thanks again for all your input and thinking of purchasing the Rinda TechMate Pro hand held

[KoolAid]

The yellow/red wire goes into the round 10 pin connector. You may want to pull it, check for corrosion at all the pins, and to make sure when you give it a turn to crank position that is is seeing power there. This wire pretty much goes directly to solenoid.

I wouldn't suggest the techmate just yet. This is a pretty mechanical engine so most of it can be diagnosed with a multimeter. I am thinking you have two issues. 1. no starter solenoid signal (bad connection maybe) and 2, you have no power to ecm.

[UNSTUCK]

You’d have to have power to the ecm for the fuel pump to run, right? Yet it seems that it doesn’t because the injectors dont fire. Hmmmmmm.

[freeheel4life]

It all starts to blend together in my brain, but is there not a 5pin relay under the lid with the fuses??

Also, Koolaid is right, the techmate doesn t give you tons of help on this engine. The one thing I have found though is that when it ends up being TAC module issues due to voltage it throws lots of codes, a bunch relating to TPS. I think they are a bunch of (82) codes.
Either way it will be like 6 active codes all at once

[LIL RED]

I found a three bank fuse cover on the wiring harness and all three were good and had power on both sides. I also have power on the small red wire that runs from the battery to the engine harness. I did trace the yellow Red wire from the solenoid to a relays on the engine harness. It tested good but having trouble finding the path back to the neutral Saftey switch.
I checked the big connector from engine harness to front console and it was all very clean no corrosion I even spread the pins apart to get better contact still no change.
I'm almost positive I don't have power at my ecu but don't have a wiring diagram to check it. Does anyone know where you can get one or purchase a schematic on the harness?
Thank for all the responses