Fiat Ducato Posted April 1, 2017 Share Posted April 1, 2017 Hi guys I own a 1997 Fiat Ducato 1.9TD AutoRoller motorhome. Bought about a year ago and discovered that it it had water ingress. Spent many many months ripping it all out and refurbishing it it. Almost completed now just doing the last few jobs. One of those jobs, was sorting out the electrics to the main 12v/240v power management and distribution unit. Was a right mess, wires connected to wires connected to wires, crimps everywhere, wires piggy backed to other wires as well as melted plastic connector blocks, a melted pin terminal on the actual circuit board and domestic 240v 2.5mm twin and earth cable used for 12v application. I removed all the cables, removed the main power unit, took it apart and repaired the circuit board, removed the melted connectors and soldered new mate-n-lok connectors in place. And following the instructions and schematics for my power unit. I connected all the cables back how they should be. But noticed that the was only a feed from the vehicle battery and leisure battery, and none directly from the alternator like the installation instructions show. Probably explains why my leisure battery wasn't charging with engine running, and why fridge not working on 12v with engine running. So I have now ran a length of 6mm tri rated cable directly from the alternator to the correct terminal on the correct connector and hey presto my leisure battery is now charging with engine running, but now my fridge is on all the time even with the engine switched off. Sorry about the long history, but finally to my QUESTION. The cable I have run directly from the Alternator shows a voltage all the time even with the engine off. Is this normal, I take it this must be the vehicle battery voltage. I was under the impression that there should be no current from the alternator with engine off. Have I connected the new cable to the wrong terminal on the alternator. The reason I ask, is the fridge and charging function works via 2 separate relays, which when the engine is switched on, provides power through the alternator cable, this action switches the relay providing power via the relay to the fridge and charger. If the alternator is always showing power (voltage) then doesn't this mean that the relay will be constantly live (switched on) and why my fridge is always on. (I've disconnected it for the minute) Any feedback, comments or advice would be greatly appreciated. Reached a halt at the moment, somebody in the past has also switched the live and neutral wires around at the Truma boiler water heater so when I connected them back up at the power unit I completely burnt out the circuit board. Really gutted as this is more expense not needed. Also my pump is not working, light is on, power to the pump, but no power going to the actual pump (there are 2 red live wires on the pump) one works and one doesn't. Water in the tank. Really weird, not sure if pump as give up the ghost where it as been left for so long not used. Link to comment Share on other sites More sharing options...
Alanb Posted April 1, 2017 Share Posted April 1, 2017 Regarding the query about your alternator connection, the simple answer, is YES. It seems that you have connected to the alternator main output terminal (B+). Due to the connection to the vehicle battery this is a hazard, with possible fire risk. For safety, please disconnect both battery negative connections and then remove your wire. The correct connection is to the alternator field terminal (D+). However as this connects to the terminal of the alternator warning light that is electrically remote from the ignition switch, the required connection can be made behind the instrument panel, or other point en-route. Reversing the live and neutral connections to your water heater, should not result in disaster. Perhaps you a refering to the 12V positive and negative control supply. Electronics do not appreciate reversed supplies. I am assuming that your pump is pressure controlled, rather than by micro switches on all of the taps. Is the wiring complete in this area? The supply from the ON / OFF switch should go via the integral pressure switch to the pump motor. The other side of the pump motor will be a negative return. Alan Link to comment Share on other sites More sharing options...
arthur49 Posted April 2, 2017 Share Posted April 2, 2017 Maybe this is useful schematic http://www.motts.org/SPLIT%20CHARGING%20SYSTEM.htm Link to comment Share on other sites More sharing options...
Fiat Ducato Posted April 3, 2017 Author Share Posted April 3, 2017 Hi all just thought I'd update this post. I have now sorted the alternator connection to my main power management unit and it is all working as it should be. Fridge comes on with engine switched off on 12v and goes off when engine is switched off. Leisure battery is charged now when engine is running and stops when engine is switched off. Finally got my pump working. And as for the water heater well the 12 pin grey connector block on the circuit board, and melted a couple of the terminals and fused the solder together on the rear. I have de-soldered it and removed it, cut off the other end as well as that had melted. Ordered a new connector to solder back to the board and the male connector to go with it. If that fails then it's £100+ for a new Truma water heater circuit board. Link to comment Share on other sites More sharing options...
Fiat Ducato Posted April 3, 2017 Author Share Posted April 3, 2017 Alanb - 2017-04-01 10:48 PM Regarding the query about your alternator connection, the simple answer, is YES. It seems that you have connected to the alternator main output terminal (B+). Due to the connection to the vehicle battery this is a hazard, with possible fire risk. For safety, please disconnect both battery negative connections and then remove your wire. The correct connection is to the alternator field terminal (D+). However as this connects to the terminal of the alternator warning light that is electrically remote from the ignition switch, the required connection can be made behind the instrument panel, or other point en-route. Reversing the live and neutral connections to your water heater, should not result in disaster. Perhaps you a refering to the 12V positive and negative control supply. Electronics do not appreciate reversed supplies. I am assuming that your pump is pressure controlled, rather than by micro switches on all of the taps. Is the wiring complete in this area? The supply from the ON / OFF switch should go via the integral pressure switch to the pump motor. The other side of the pump motor will be a negative return. Alan Hi Alanb Thanks for your reply, yes you were right, I had connected it to the B+ and not D+ terminal instead. All sorted now, all working correctly. Pump working as well, had the 2 red push on connectors in the wrong place, closer look there was a terminal sunk in slightly, and 2 other terminals further out. As for the water heater, yes the 12v supply cable that runs to the water heater from the main unit, I connected brown - live and blue - neutral. However on the water heater side the wires were reversed for some mad reason brown - neutral, blue to live. Started burning, smelling and melted. Before I could disconnect the wires, the damage had been done, just not sure how much damage would have been done. Obviously fuse couldn't blow as power was going through negative side. solder from 3 of the terminal pins had fused together on the rear. I have de-soldered the melted 12 pin connector block and removed it from the PCB board, cleaned it up and ordered a new connector to solder back on. Not sure what other damage would have been done. Link to comment Share on other sites More sharing options...
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