ALarms Until BOTH Engines Started?

[Captainjeff296]

Hello!

I have an issue on my 1998 3000 SCR. I have twin 4.3L V-6's and when I start either engine, the alarm continues until I start the second engine, then the alarms stop. Also, when I turn off the port engine ignition, nothing happens until I shut down the Starboard engine, then both shut off.

All fluid levels are good and oil pressure is good. Not sure why this is suddenly happening! All worked fine until recently.

Anyone have any ideas wher to start looking?

Thanks in advance for your help!

[pascavone]

both alarm and end shut down fuctions: sound like a bad ignition switch, or someone crossed a wire under the dash, or wire poped off the ignition.

pull the panel down and check.

[Captainjeff296]

I pulled the panel the other day and didn't notice any wires loose, I will check to see if the ignition switch is bad. What's wierd is, it allows the port engine to START fine, but won't shut down. I am going to head down there today and check lots of wires! I have been doing some reading and it appears some people say it could be a bad sensor, but not sure why it would shut down when the OTHER engine starts?

I'll dig into my wiring and se what I can find!

[Captainjeff296]

Okay... After further investigation... The ignition switches appear to work fine on both engines. When I start one engine, the alarm howls away without stopping. If I do not start the other engine, the ignition switch will shut the engine down. This works on both sides. The problem (and the solution) happens when I start the OTHER engine. The alarm stops as soon as the second engine is started. As soon as the second engine starts, the engines will NOT shut down until BOTH engines are shut off by the key.

The EMERGENCY cut off works on both engines separately when both engines are working. this is just a WIERD problem and I am sure it is just a bad ground somewhere in the system... Only question is... WHERE???

[shrew]

The engine alarm you are desciribing is there to verify the engine warning system is working. This should occur whenever you set the keys to the ACC. position. It should stop as soon as you successfully start the engine. On my 97 2800, when I had the stock 7.4 (454) installed the alarm would sounds constantly when the key was in the ACC position, and stop once the engine was started. When I repowered with an 8.1 496) the alarm only sounds for about 3-5 seconds when the key is set to ACC, then stops. Either is expected behavior.

I do have a few questions:

1) Are you setting both keys to ACC before starting?

2) With both keys OUT of the ignition, if you insert the Port engine key and turn the key to ACC. I would expect the alarm to sound. Once you start it, I would expect the alarm to stop.

3) With both keys OUT of the ignition, if you insert the Starboard engine key and turn the key to ACC. I would expect the alarm to sound. Once you start it, I would expect the alarm to stop.

What you describe sounds alot like expected behavior. However, I would not expect that you would need to shut down both engines to stop one engine. That makes no sense. I don't think this is a ground issue, however it does sound like someone may have wired the starters incorrectly.

[pascavone]

all the key dose is ground out the ignition to kill the engine, you have one key not doing that. if you jumped out the wire i bet the engine stops, so the key ground is faulty.

the 2nd engine wire is shorted to the first. One key should never kill two engines, trace these wires.

the alarm is secondary, the alarm only know the engine is not turing and then squels.

The 2nd engine running will turn off the alarm.

The starting curcuit is not involved, but the main power lead comes off the 80 amp fusible link that sits on the top of the hot lug on the starter.

hot wire a power lead from the battery to the key with a long wire and see if you have the same problem by jumping out the key switch.

[ss3964spd]

Originally Posted by pascavone

all the key dose is ground out the ignition to kill the engine, you have one key not doing that. if you jumped out the wire i bet the engine stops, so the key ground is faulty.

You certain about that Pas? I always thought turning the key to the ON and Start positions supplied 12v to the ignition circuit, and turning the key to the OFF position killed the 12V to the ignition circuit. Turning off the 12V is diffent than grounding (shorting) out.

Dan

[pascavone]

we are both right.....

a 1998 engine probily has an module that shorts or kills the ignition.

they don't run the hot lead all the way to the key switch anymore, not in cars since the 1960's.

they use a relay, and the key grounds out the relay and the relay kills the ignition circuit.

[ss3964spd]

Jeff, you said the port engione will start fine but won't shut down when you turn the port engine key to "Off" when the other engine is running.

Question: With the starboard engine key in the Off position can you start AND stop the port engine with the key?

[ss3964spd]

I'm no electrical guru but I believe we've got to get the terminology right for effective troubleshooting.

We're talking about a 12V system where the negative side is ground (opposed to a positive side ground as used in some British cars). As such only the positive side is switched. A relay, as I understand it, has 2 sides, low amperage and high. When 12V is provided (switched on) to the low side the relay closes (normally Open) it completes the circuit on the high side - providing 12V to the load.

In my mind, when you "ground" something you are, basically, shorting out the circuit. I don't believe that's how it works to kill the ignition.

Regardless, if Jeff's answer to my question above is Yes, then somehow the starboard ignition system is back feeding 12V to the port ignition system.

Dan

[pascavone]

chapter 10 of the book says:

turn the key to run, no horn, then jump post "A" postitive battery to "B" good ground.

if no horn, then jump "C" positive to "D" to a good ground.

The horn sounds because it is wired to the tachometer, no RPM signal is an alarm, start engine then RPM and no alarm.

if the swtich is good next siwtch to check is your Engine neutral safety switch on the drive control or then lanyard switch could just be rusty, and need a shot of WD-40.

those switches will control the engine starting and could be shorted to the 2nd engine.

the book has step by step testing of each switch by jumping them out or using a multi meter.

Example is my masserator, both switchs stuck solid, hung them down soak them with WD-40 and the crap started to fly..... still don;t need it but its a conversation peice.

[Captainjeff296]

Thanks to all who have contributed to this question! Okay... I will try to answer everyone's questions. When go to start the engines I insert BOTH keys in the slots but do not turn them unil I am ready to start. It doesn't matter WHICH engine I start with (Port or Starboard) I turn the key to ACC Alarm... I START the engine... Alarm... It NEVER shuts up. If I turn the key to OFF on the running SINGLE engine... It shuts down as advertised... Alarm stops when I turn the key off. This works with either PORT or STBD Engines.

Okay.. Here is where it gets goofy!

I start EITHER engine... ALARMS CONSTANT... I start the second engine... Immediate peace and running engines!

I shut down the port engine by the key... NO SHUT DOWN. (All instruments go dead... no charge, no engine indication on the guages... but port and stbd engine keeps running.
I leave the port engine key OFF... and turn STBD engine to OFF... BOTH ENGINES shut down.

I cannot for the life of me figure out what's going on? This began without any changes of any kind to the ignition or wiring. So, some component must have failed or something rattled loose I would assume?

Again, than you all for taking time to assist me with this!

[ss3964spd]

"Here is where it starts to get goofy"? It's already goofy! Something is feeding 12V to the other side Jeff.

First off the ACC (Accessory) is not actually ACC, but ON or RUN. The ignition switches have 3 positions; Off, On/Run, and Start. When the key is moved to On/Run the ignition system for that engine is energized as is the Alarm system. The alarm system is now waiting for input from sensors. With the key in the On/Run position the gauges for that engine are also supplied with 12V and that 12V feed is seperate from the 12V feed to the ignition system. The Start position does nothing more than engage the starter for that engine. When the key is switched to Off it kills the 12V feed (opens the circuit) to both the gauges and the ignition for that engine.

For the most part the electrical systems for both engines are completely independent. However, based on the symptoms you've provided, there is obviously at least one component that is shared by both.

Questions: Is there one or two emergency kill switches at the helm? When you turn either key, one at a time, to On/Run do ALL the guages light up or just the ones for that particular engine? Are there two seperate alarm buzzers under the helm or just one?

You're going to need to track down what is common electrically between the two, specifically the ignition systems. My first guess, based on how you describe what the alarms are doing (but without the benefit of a wiring diagram) is that the alarm system uses a single module for both engines.

Dan

[Captainjeff296]

Thanks Dan! You are right... I am sure SOMETHING is sharing power from SOME component. (I just can't seem to find it!)

To answer your questions I have TWO kill switches and they BOTH kill their respective engines as advertised.

Both guages work independently to their respective engines. So to that end, both of those systems work independently as they are supposed to.

There are TWO alarms the sound comes from two different places under the dash board, so they are separate as well.

As I said, I can START and STOP the engines separately if I only start ONE engine... Just the darned ALARM won't shut up until I start another engine.

Hope this helps! Thanks again!

[ss3964spd]

Jeff,

Question: With both engines running and keys in the Run position will the port engine kill switch shut down the port engine?

Even though you have two seperate alarm buzzers there might still be only one alarm control module that takes feeds from both engines. Given that you can start either engine and the alarm continues to sound until you start the other engine it seems to me the alarm system is suspect.

You state there are two alarm buzzers. If you start the starboard engine the alarm sounds until the port engine is started. Or, if you start the port engine first the alarm sounds until you start the starboard engine.

Another question then: If you start, say, the port engine, does the alarm for that engine keep sounding or is it the other one? Same question if you start the starboard engine first - which buzzer is sounding? Or is it always the same one?

Dan

[Captainjeff296]

Dan,

Both Emergency Kill Switches work as advertised with BOTH engines running. (I thought of the same thing!)

I am definitely suspecting the alarm generation system... I just don't know what it looks like or where it is located?

The alarms persist no matter WHAT sequence I start them in... Port first or Starboard first. the alarm will not stop intil BOTH engines are started.

The respective alarm systems stay on until the other engine is started. The alarms sides never change.

Thanks again!

Jeff