Cut out switch/ module 5.& merc

[rburg]

I have a 97 5.7 mercruiser with 2nd gen alpha one. The cut out switch is working only %50 of the time have tried a new one and even directly ground the white and green wire which I believe goes to the distributer or the ignition module there is the same color wire going to each. There are two grey ones to the coil and one purple (power) It seems better when its cold but at random times the cut out switch will not kill the motor even if you hold it, it sometimes wont even make the engine skip at all so would this mean the module is not shorting the coil or is there something else im missing???

 

[rburg]

Re: Cut out switch/ module 5.& merc

Surprised I got no help with that..... Anyways I found out that it is the module that gets shorted which then takes away the ground to coil. My problem now is that at higher rpms sometimes at the 1000 mark but always higher then 2000 it cuts out ground to the coil tried a new coil but it looses ground from modlue. Is this more likely to be the pickup not sending the signal or is module cutting out? any ideas would be appreciated.

 

[John_S]

Re: Cut out switch/ module 5.& merc

I didn't see your original post, but yes, on T5, the input from the shift interupt feeds the ICM. To activate the input, the interupter grounds it. I don't have access to the wiring diags right now, but believe the ICM grounds the input to the distributer pick-up sensor. This stops the pulses coming from the sensor, and hence any firing of the ignition.

For clarity in understanding your problem, at 2K you engine dies, and then when rpms drop, it fires back up? or does it just start missing? While running on muffs or at dock, you have disconnected the shift interupter bullet plug, and the problem still occurs?

Is this a 2brl L model, which doesn't have knock control module or a LX or Mag which does?

Verify you have the right ICM for your model and alpha drive. A bravo module will not work. Make sure the ground wire is attached to the metal tab on the ICM. I think this will come down to verify all good connections and replacing dist sensor, and if still fails, the expensive ICM.

BTW, I am assuming you have a carbed model and not efi or mpi.

 

[rburg]

Re: Cut out switch/ module 5.& merc

Thank you so much. Yes your right 2 barrel no knock sensor and yes unplug the interupter switch and no change. It is a miss not a stall, still drivable but at times its very bad. Just today I changed the pick up sensor in the dist with the updated one (with a extra wire to directly ground) still does it but alot better. I see the main plug to the coil but not the extra ground on the back you speak of I will look harder for that tomorrow. It is a T4 propper leg match up alpha one gen two.Thank you again

 

[John_S]

Re: Cut out switch/ module 5.& merc

A black wire with ring terminal should be on one of the ICM mounting tabs. There are also black wire grounds to the carb by elec choke and intake. I assume you have already replaced dist cap and rotor, along with mentioned coil and sensor.

Any water dripping out of icm? Acts up warm or cold? and just to clarify, when you activate the interupter it does kill the engine.

 

[rburg]

Re: Cut out switch/ module 5.& merc

It seems more when its warm. This is a new motor with new carb and now everything but the icm is new. The switch does kill the motor but a week ago it would only do it %75 of the time after a bunch of adjustments to the linkage and switch it seems to kill engine everytime. I dont remember a second ground to that icm but i will run one tonight and reset timing. Thanx again and no water at icm