Kad300 not starting intermittently

[kashurst]

This looks a better: You will need to connect the two negative connections together as it is an isolated output.
Victron Energy Orion-Tr DC-DC Converter 12V-12V 18A (220W) - Isolated

 

[kashurst]

Remote voltage sense (i.e. at the load end of the wire to compensate for voltage drop in the cable from the regulator to the load)?

I just looked at the wiring diagram. It is a bit odd teh way Volvo do this becasue they came up with teh idea of having double pole isolation - basically two relays that kind of disconnect the ECU from the 12v circuits. I have studied their diagram and cant understand quite what they were trying to achieve.
Meanwhile back to teh DC to DC converter. The volvo jobby does have five wires. Now this is from memory and obviously needs cross checking. I replaced my DC to DC converter about 10 ish years ago on a KAMD 300. There are five wires. From memory there is a 12v in, a -ve or 0v in, 2 x 12v out which are just connected together in the harness and a -ve or 0v output. However I am very sure (but check) the -ve in and -ve out on the DC to DC converter are actually just connected together. So the whole five wire thing is I believe a hangover from whatever the previous generation of wiring harness required/was made like.

 

[Iwilliams0511]

I just looked at the wiring diagram. It is a bit odd teh way Volvo do this becasue they came up with teh idea of having double pole isolation - basically two relays that kind of disconnect the ECU from the 12v circuits. I have studied their diagram and cant understand quite what they were trying to achieve.
Meanwhile back to teh DC to DC converter. The volvo jobby does have five wires. Now this is from memory and obviously needs cross checking. I replaced my DC to DC converter about 10 ish years ago on a KAMD 300. There are five wires. From memory there is a 12v in, a -ve or 0v in, 2 x 12v out which are just connected together in the harness and a -ve or 0v output. However I am very sure (but check) the -ve in and -ve out on the DC to DC converter are actually just connected together. So the whole five wire thing is I believe a hangover from whatever the previous generation of wiring harness required/was made like.

The two inputs and two outputs are common within the Volvo unit so do not understand fully but as you say I think it is hangover from a previous rollout or it was added as an improvement as they were getting starting issues.
The 5th wire is a common wire.
If I find a 2nd hand Volvo unit I will go for that if not I will try a Victron unit

 

[petem]

The two inputs and two outputs are common within the Volvo unit so do not understand fully but as you say I think it is hangover from a previous rollout or it was added as an improvement as they were getting starting issues.
The 5th wire is a common wire.
If I find a 2nd hand Volvo unit I will go for that if not I will try a Victron unit

These units are prone to failure so you'd obviously need to ascertain that a second hand one isn't also defective.