Thanks for the link. I'll take a look at that too.

Steve has almost the same thing. It turns the off and back on. But more random. It has been in and out of the shop for the last 2 years. No one can nail it down. Been down almost every street with the internet and shops. Bad grounds, bad batteries, bad computer, bad IAC, bad 50 amp circuit protector, bad fuel pump ,bad ignition switch, bad safety switch, bad coil, bad wires, and the list goes on and on. Funny the local shop has pretty much given up. So Ill do some more digging this off season into his boat. Yes I have and the shop have scanned the engine several times with nothing.



^^^^^^ This will now be on my list this winter to check. This is a new one I haven't seen. Thank you!

Thanks for all the info. I think I will look at the alternator first and then work my way towards the other stuff. I'll report back with findings after the weekend.

Have you replace the TACH and or checked all of its harness adaptions here ? Connections at cannon plug ? transom harness connections ?

I know I replied to this guys post. Maybe its interference from the empty beer bottle and beer koozy ? haha

Where is this guys post ?

I ended up swapping computers over the weekend and the problem followed. So now I guess I need a new PCM.

Where can I find one for a stock 2006 496mag non HO motor ?

Will need your serial number to look it up

Serial # is: OW628151

number on the PCM is 866090-003, but I can't seem to find that exact number anywhere. I'm not sure if the 003 on the end is a revision # or it means something else. I find variations of 866090Txx numbers out there, but nothing that is the same as my #.

The original part number was 866090T01
Genuine Mercury & Mercruiser parts. 866090T01 PCM Genuine OEM Mercury Marine-Mercruiser part

BAM shows it has been superseded by 866090T05
Genuine Mercury & Mercruiser parts. 866090T05 PCM Genuine OEM Mercury Marine-Mercruiser part

Looks like cheapest is at ebay but not that much cheaper.
BRAND NEW Mercury Mercruiser Quicksilver OEM PCM PN 866090T05 | eBay

ALLDodge, Thanks for the clarification on the part #'s.

The ebay auction has a different part # on the label of the PCM that is in the picture. I emailed him to clarify.

Chit these things are expensive !!

for the 555 controller most likely an alternator wire issue would should in the scan as a Voltage fault. Wanted to mention this from the post that were brought up about that issue. Also voltmeter testing would have found that problem as well. always start at the battery and work way thru all the other power systems, ie starter cables, power relays and or breakers, alternator and so on.

If you want to send me your PCM I can see if I can fix it . If I can not for a fix - a very min charge like 50 bucks with shipping back to you would be included.

If I can fix it of course the changes will apply depending on what is the issue(s). Not all PCM 's are repairable.

I will not be available until next Monday. So far I have fixed about 60 percent of the 555 PCM's / ECM's With that said I have not done that many but gaining more ground for that part of the business.