Mercruiser 8.1L not starting

[Craig Poole]

I have a Bertram 35 with twin mercruiser 8.1L DTS and Smartcraft. The transmissions are ZF63A with electronic shift. I recently had the starboard transmission out for repair. After refitting the transmission both motors will not start. There is no power at all to the digital controls. The ignition switches do nothing. I have checked all earth and positive terminals from the batteries etc. The motors turn over easily by passing the starter relay.There is power in and out of the 50 amp circuit-breaker. I have checked all fuses.
Any advice or help would be appreciated. A wiring diagram for the engine side of the harness would be great.

 

[alldodge]

There is a neutral safety switch on the transmission, is the plug connected?

Since both will not start, look for something not connected like a terminator on the CAN buss. If one cable is not connected then the CAN buss will not be able to transfer info

Your motors have 2 connects, one is electrical and the other is the network cable

 

[paulswagelock]

Look for the 5a clean power fuse near the batteries to be disconnected or blown.

 

[Craig Poole]

There is a neutral safety switch on the transmission, is the plug connected?

Since both will not start, look for something not connected like a terminator on the CAN buss. If one cable is not connected then the CAN buss will not be able to transfer info

Your motors have 2 connects, one is electrical and the other is the network cable

Alldodge, Thanks for the reply.All the terminators are connected. What is the purpose of the terminators. Are they just an end for the wiring or do they complete a circuit. Can they fail.
Not sure about the 2 connects on the motors. Could you explain a bit more. There only seams to be the main harness that comes from the starter to the 50 amp circuit breaker. There is a live feed to the fuse (red ppl). Where are the 2 connects.

 

[Craig Poole]

Look for the 5a clean power fuse near the batteries to be disconnected or blown.

Thanks for the reply. I can find only 1 clean power connector on top of the motor near where the transmission harness joins the main harness. There has never been a fuse in the 2 pin clean power connector. There is a fuse near the battery that is meant to be connected to the DTS on a single engine setup. Fitting instructions state this is not to be connected with twin engines. Please keep the ideas coming. I am in Australia with beautiful boating weather at present and desperate to use the boat.

 

[alldodge]

Alldodge, Thanks for the reply.All the terminators are connected. What is the purpose of the terminators. Are they just an end for the wiring or do they complete a circuit. Can they fail.
Not sure about the 2 connects on the motors. Could you explain a bit more. There only seams to be the main harness that comes from the starter to the 50 amp circuit breaker. There is a live feed to the fuse (red ppl). Where are the 2 connects.

There is a 14 pin engine harness that goes from the motor to the Helm. There is also a CAN buss connector used to transfer digital info from the PCM to the DTS. Your drive by wire so the CAN bus has terminators on all cable ends, and if one is missing its like removing a cap off a water hose, the water just pours out and no pressure develops (so to speak)

 

[Craig Poole]

There is a 14 pin engine harness that goes from the motor to the Helm. There is also a CAN buss connector used to transfer digital info from the PCM to the DTS. Your drive by wire so the CAN bus has terminators on all cable ends, and if one is missing its like removing a cap off a water hose, the water just pours out and no pressure develops (so to speak)

View attachment 331200

Thanks all for the replies. All sorted. Had a mercruiser technician come and look. The wiring was badly installed with the new motors. Within an hour he had pulled all the CAN BUS connectors out and removed some bad 12 volt feed and reinstalled both harness's correctly.