Not sure if this would help you, but if you have your motors serial number, this parts catalog may give you the correct part number to look online.

https://www.mercurymarine.com/en/us/parts-and-accessories/parts-catalog

 

The thunderbolt V modules are no longer made

806961A01 Is the replacement kit

but at around $590 I would seriously look at non-mercruiser marine distributor

 

I have the thunderbolt V as well, in used the Mercury online catalog which rolls it up to this module, $79 from quicksilver on eBay. Are saying it won't work?
https://www.amazon.com/dp/B001HBN0Y...001HBN0YY/?coliid=I3HS40FFH7HXEG&colid=30FS3CMRG1HJL&psc=1&ref_=lv_ov_lig_dp_it

 

Just to be sure....have you tried installing the bad one on the other engine? Sometimes what looks like the problem on these ignition systems turns out to be something else.

 

I swapped out the module from the starboard engine (which had started right up) to the port, and it started immediately.

Before spending $590 on a replacement, i think exploring other distributor options are in order. I can probably come close to changing out the distributors on both engines for the cost of the module.

 

Put the part number in on eBay
Ignition Control Module 131300-2240 T4408 2110
I believe this is your part
Also check rock auto

 

The original ND part is
Ignition Control Module 131300-2230
But if it can be crossed to a current ND number $50+/- is a whole lot more reasonable

 

My last try , lol
Call Denso, tech support US , 1-888-800-9629 see what their thought are on your parts, maybe they can get you in the right direction
Won’t hurt !!!
GOOD LUCK

https://www.densoproducts.com/denso-technical-support

 

Skip all the hassles of buying and installing the ICM and remove all that crap. Switch the distributor out with a new one that does not need the ICM. It’s cheaper, improves fuel consumption, and more reliable. I got mine from JEGs. There are many threads on the subject here. It takes a DUI marine distributor. It was a job I could do with guidance.

Let me add, this was the best move I’ve made with my old girl. If you don’t know how old your wires are it’s a great time to change them as well. JEGs sells the complete set up and it’s still cheaper than buying a new ICM

 

Skip all the hassles of buying and installing the ICM and remove all that crap. Switch the distributor out with a new one that does not need the ICM. It’s cheaper, improves fuel consumption, and more reliable. I got mine from JEGs. There are many threads on the subject here. It takes a DUI marine distributor. It was a job I could do with guidance.

I've had DUI distributors for 6 years in my 454s. Highly recommend.

 

I appreciate the feedback and suggestions. If finding a replacement module was as easy as just ordering one (which it should be), I would certainly go that route. But apparently it’s not! I’m going to research changing out to a complete new distributor/ignition setup. Knowing that I can get parts for maintenance is comforting.

 

You can find them but at a high cost. Do not buy a used one! These things are outdated and you will need the updated wiring harness to connect it to your motor. Look at the price of both options

 

Depends what you need that appears to be the internal sensor module, the part that picks up the chopper wheel motion inside the distributor.
It is not the external ICM

 

Ah yes, thanks

 

On ebay if you type in mercruiser thunderbolt IV ignition module you find about 20 of them used for about $200.

Thats how i got my TBV module when i swapped a 4.3 for a 5.0 sold the 4.3 module for what it cost for the other one...