For the first time I tried using my Rinda Techmate scanner on my 7.4 MPI engine to see if I had any codes. When I first hooked it up it did recognize my MEFI3 configuration. When it went into diagnostic check, which I am assuming this is where any codes wold be stored, I received the following message, "General warning #1 telltale indicator has been set". I have no idea what that means.

Have to ask, do you have the correct adaptor harness to plug into the 10 pin DLC connector ? Do you have the manual for using Diacom ? Engine - first is key off plug the correct adaptor / scan tool side to the correct DLC 10 pin connector on the motor side. - turn the key on and or start the engine (if it does start). If not just leave the key to the on position. Make sure your battery voltage is normal 12.7 v for testing with key on position or running the motor at 13 to 14 v. You need to properly set up the correct prompts / flow chart menu on the scanner for your app to proceed the scan correctly to receive the data.

The Techmate scan tool can activate ECM outputs for diagnostic purposes. Selecting the ECM outputs test menu, this will check the ECM in order to determine its version type. You most likely chose the menu listings of the ECM outputs the techmate along with MEFI 3 (mercruiser version) is capable of triggering. These outputs are active. Output on the ECM Pin # J1-21 Mercruiser MEFI 3 is general warning # 1 - this the OUTPUT side of the ecm diagnostic - you can clear this code. Are you pressing the test key on your scanner as this most likely activated the output test beforehand ?

I believe I got the correct adapter. It came with the scanner and does plug into the 10 pin connector. Is there a way to verify I did get the correct adapter? I do not have the diacom manual. The manual that came with the scanner does not have a list of codes. I did proceed to Engine - first is key off plug the correct adaptor / scan tool side to the correct DLC 10 pin connector on the motor side. - turn the key on. I did not start the engine but left the key on. My battery voltage was over 12.7 VDC. I did not set up the correct prompts / flow chart menu on the scanner for your app to proceed the scan correctly to receive the data. Not sure how to do this.The unit did prompt me to answer yes for I/O and then displayed the MEFI3 version which is correct. I also did see it display ECM Pin # J1-21. This afternoon I will erase this code. Still not sure what menu will show any codes.
Thanks

I guess I am surprising myself here as I remembered completely the ECM pin # J1-21 for the MEFI 3 is general warning # 1 from the output test.

Techmate I believe the correct adaptor for MEFI 1 thru MEFI 4 b is adaptor # 94005 to connect to the DLC 10 pin connector motor side from the scanner.

The Techmate scanner for MEFI controllers can cover thru MEFI 5 C. - FYI.

You need to get the techmate owner operator manual or call Rinda for your instructions.

My rhinda scan tool bought through rhinda didn't come with a manual with codes and their meanings. Found tthem in the merc service manuals think it was #23