ICM

[juliolop]

Hi, can the ICM be bypassed for troubleshooting purposes?​

 

[Bt Doctur]

Define trouble shooting?

 

[Scott Danforth]

what problems are you having? what are you working on?

 

[juliolop]

yes, old cars didn't have electronic ignition, in case you find a failure in your ICM, can you not put the wire coming from the module to ground? the ICM just make a path to gnd, and we know the advanced ignition will not be present, may be we need to change the coil too, but if it works can save you at sea. Am I wrong?

 

[Bt Doctur]

Have no idea what your rattling about??????????????

 

[Fun Times]

Are you theorizing what if, or do you believe the module is bad at the moment?

Are you talking/have a fuel injected engine or Carbureted?

If the module doesn't seem to be functioning properly, then there is a test found inside the service manual you could follow and below are some different style testing ideas that come to mind for the ignition control modules not found in the Mercruiser service manuals.

Try connecting the ground side of your test lamp to the battery positive cable. Touch the negative side terminal of the coil while a helper cranks over the engine. The test lamp should blink repeatedly as the engine cranks. No blinking = bad module, pickup coil, points etc. Further testing is required to pinpoint the problem. Blink but no spark = bad ignition coil. Use a known working timing light connected to the high tension coil wire to cap to check for consistent flash then move timing light inductive pickup sensor to a few plug wires looking for a flash as the rotor turns... http://forums.iboats.com/forum/engin...mercruiser-165

If you get spark from the coil tower then the module is working.
Your "expert tech" should be able to figure this out rather easily.
If you set your meter to dc volts and connect the positive to the negative side of the coil and the negative side to a good ground, with the ignition "on" hold the white/green wire from the module to ground for a few seconds, if the voltage drops to 7-9 volts, then returns to 12, the module is good.. http://forums.iboats.com/forum/engin...76#post4719776

Don't forget that you have an ignition sensor normally mounted under the distributor cap that tends to malfunction much more often than the ICM.... But one could theorize that if the sensor under the cap is still good, then you could possibly figure out a way to bypass the Carbureted designed ignition control module but you won't have much degree advance to safely run the engine at high RPM.

 

[thumpar]

What do you have? That is like asking a question about a car without knowing what car/engine it has.

 

[juliolop]

hi everyone.
questions ...
as you know my engine is a 2001 Vortec CID 305 2BBL carb, with ignition V w/o knock sensor.
is it possible to add this knock sensor and the related module?
is it a good idea?
do I have to change my actual ICM module?
any other addition? or modification?
I also have a sensor in the time cover but is not connected. why ????

 

[Fun Times]

questions ...
as you know my engine is a 2001 Vortec CID 305 2BBL carb, with ignition V w/o knock sensor.

Well to be honest no we didn't know as you never mentioned it within this topic until now...

is it possible to add this knock sensor and the related module?

Possibly yes... Post up your engine serial number in order to double check a few things.

is it a good idea?

We're not even sure of what your original problem is to even at least try to help guide you to a solution as we had many question for you that went unanswered.:noidea:
Adding a knock sensor could only just help hide a severe problem but not necessarily repair it.

do I have to change my actual ICM module?

No you shouldn't have to.

any other addition? or modification?

You "may" have to install a different design wiring harness that utilizes the knock sensor connectors.

I also have a sensor in the time cover but is not connected. why ????

That sensor is a GM factory mounted Crank Shaft Position Sensor that Mercruiser didn't start using until 2003. You'll need to leave the sensor there as it's used as a plug to keep oil from leaking out....Or I do believe I've seen plugs sold somewhere that you could remove the sensor and plug the hole if desired.

http://www.mercruiserparts.com/bam/s.../31837/2697/50

 

[thumpar]

Do you have an issue with it right now?

It may help to put your engine and drive info in your signature. Serial number is a plus.

 

[achris]

as you know my engine is a 2001 Vortec CID 305 2BBL carb, with ignition V w/o knock sensor.

Nope, didn't have even the first clue. Just between you and me, I was thinking you might have had a 1968 Mercruiser 120. With 500,000 members on this forum, even Einstein would have had a tough time remembering every members' engine details.
Maybe in the future, at the beginning of each new thread you should add your engine details, and to get the best possible results and fastest answers, include your engine serial number. Or do as many do, put it all in your member signature, like I have.

is it possible to add this knock sensor and the related module?

Yes.

is it a good idea?

It's neither good nor bad. Why do you want to do it? Are you having fuel issues? That's the only thing it does. If the fuel is of low quality (or old) it will retard the timing in an effort to reduce fuel detonation. BTW, Merc deemed it not necessary on those engines, and if you don't over-prop (propeller pitch too high and causing the engine to be overloaded all the time) then there is no good reason to have it.

do I have to change my actual ICM module?

No.

any other addition? or modification?

To add the knock sensor? No.

I also have a sensor in the time cover but is not connected. why ????

You may find that is just a plug. All the engines, be them carb or EFI use the same timing cover (cheaper than manufacturing 2 different covers). On carb enignes they just put a plug in, not an actual sensor. It's just there to stop oil pouring out....

Chris....

 

[juliolop]

Nope, didn't have even the first clue. Just between you and me, I was thinking you might have had a 1968 Mercruiser 120. With 500,000 members on this forum, even Einstein would have had a tough time remembering every members' engine details.
Maybe in the future, at the beginning of each new thread you should add your engine details, and to get the best possible results and fastest answers, include your engine serial number. Or do as many do, put it all in your member signature, like I have.



Yes.



It's neither good nor bad. Why do you want to do it? Are you having fuel issues? That's the only thing it does. If the fuel is of low quality (or old) it will retard the timing in an effort to reduce fuel detonation. BTW, Merc deemed it not necessary on those engines, and if you don't over-prop (propeller pitch too high and causing the engine to be overloaded all the time) then there is no good reason to have it.



No.



To add the knock sensor? No.



You may find that is just a plug. All the engines, be them carb or EFI use the same timing cover (cheaper than manufacturing 2 different covers). On carb enignes they just put a plug in, not an actual sensor. It's just there to stop oil pouring out....

Chris....

sorry I don't even know how the post came to this forum, I must have done something wrong for sure, anyway, ok ,thanks,
the question came up because someone mentioned that it could be a good idea,
and thanks again for the suggestion