New Alternator: Fridge & Heater Don't Work

[Altinatom]

Hi
All electrics OK before setting off on a trip. Alternator failed. Fridge (Dometic RMT 7655) & Heater (Trumatic C6002) stopped working. New alternator and starter battery fitted. Fridge & Heater still don't work. Checked all accessible fuses & connections. Removed and refitted all fuses to Schaudt EBL 225 to identify any faults on a particular circuit. Nothing found. Fridge & Heater work OK wired to a spare battery, so not PCB's. Any ideas?

 

[Mr Colpot]

Do they work on Gas? If just electric not working maybe there is a trip on the 240v feed (we have one hidden away in a floor box which isolates the fridge and boiler)

 

[Altinatom]

Thanks for the info.
Sorry, I should have given more detail. Neither of them work on anything when using the controls. The control led's flash for a moment, then go off and nothing happens. But, both work fully (gas and electric) on a spare battery.

 

[Beryl]

Is it possible that your leisure battery is toast and it's coincidental with having the alternator and starter battery replaced? I wouldn't expect the heater and fridge control panels to be running off the starter battery.

 

[Altinatom]

Thanks for your reply.
Again, I should have said - the leisure batteries are OK.

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[GeoffnDee]

Check for separate fuses close to the starter battery, 1 x 20amp (not the larger 40/50 amp one)

 

[nicholsong]

Check the D+ connection from the alternator.

 

[63720]

I would email Udo at Schaudt, I've used him in the past and received a reply solution in hours.

 

[Altinatom]

Check for separate fuses close to the starter battery, 1 x 20amp (not the larger 40/50 amp one)

Thanks. Will do.

 

[Altinatom]

I would email Udo at Schaudt, I've used him in the past and received a reply solution in hours.

Thanks. Will do.

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[Altinatom]

Check the D+ connection from the alternator.

Thanks. Will do for completeness. I hadn't checked as I assumed it would not have any impact on the fault which is present when the engine is not running and the D+ is not switched on?

 

[TrixBC]

Isn't it the D+ connection that triggers the 3 way fridge to run off 12v?

 

[jezport]

Have you checked the voltage at the units?
Maybe the dodgy alternator has damaged their circuit boards?

 

[Altinatom]

Isn't it the D+ connection that triggers the 3 way fridge to run off 12v?

Thanks. Yes, that is my understanding as well.

 

[ChrisL]

Sometimes when a diode fails in an alternator you will get ac current in your dc circuit, maybe this has effected the circuit boards, perhaps a member with electronics experience can confirm or deny this.

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[TheBig1]

If it works from a different battery, it's not the fridge. There are 3 12v supplies that effect the fridge. D+ which triggers the relay to run on 12v. The 12v to supply the heater that is switched by the relay and a permanent 12v feed for the control boards

as it flickers, I would say you have a bad connection for the control board feed

 

[autorouter]

There is a 2A fuse labelled 'Control AES' on the EBL225 front panel. You say that's been checked, did you check it with a meter or just visually? If it's OK. check with a meter on the fuse slot terminals. One of the terminals should be about +12V, the other one will probably be about zero. That will tell you if the EBL is sending power to the fridge control board.

 

[Altinatom]

There is a 2A fuse labelled 'Control AES' on the EBL225 front panel. You say that's been checked, did you check it with a meter or just visually? If it's OK. check with a meter on the fuse slot terminals. One of the terminals should be about +12V, the other one will probably be about zero. That will tell you if the EBL is sending power to the fridge control board.

Thanks. I check fuses with a meter to be sure they are OK. I'm a novice and learning on 12v testing. Do you mean to measure the voltage seperately from each fuse slot terminal to a convenient earth, instead of across the 2 fuse slot terminals?

 

[autorouter]

Do you mean to measure the voltage seperately from each fuse slot terminal to a convenient earth, instead of across the 2 fuse slot terminals?

Check the terminals separately, to a convenient earth. One of them should be a definite positive, about 12V. the other could be anything, probably zero if the wiring is OK.

If you want a convenient earth, the 'Additional Charger' terminals have one. Pin 2 goes to the leisure battery incoming supply, and Pin1 is a good earth. That pin2 is good for a quick check to see if the leisure battery supply is reaching the EBL

 

[Altinatom]

Check the terminals separately, to a convenient earth. One of them should be a definite positive, about 12V. the other could be anything, probably zero if the wiring is OK.

If you want a convenient earth, the 'Additional Charger' terminals have one. Pin 2 goes to the leisure battery incoming supply, and Pin1 is a good earth. That pin2 is good for a quick check to see if the leisure battery supply is reaching the EBL

Thanks for the explanation - I'm learning My understanding now is that I could use this approach on any 12v system to test any and all fuse connections, if and when required. I would not have thought of testing the fuse connections. I was going to test the terminals labelled 1 to 21 instead. After testing the voltage at the fuse connections should I then do the same with the 1 to 21 terminals as required, and then work my way along the circuit to the appliance?

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[autorouter]

Do you have the EBL225 manual? Near the end is a wiring diagram, which tells you the fridge control board supply goes out through Pin 4. And all the other info you might need. I downloaded it from the Schaudt website. It's in German, but the manuals have English versions. You select the manual you want, it asks you for an email address, then they send you an email with a link to download it. You might have to register, it's so long ago I can't remember if I had to or not. All free.

 

[Altinatom]

Do you have the EBL225 manual? Near the end is a wiring diagram, which tells you the fridge control board supply goes out through Pin 4. And all the other info you might need. I downloaded it from the Schaudt website. It's in German, but the manuals have English versions. You select the manual you want, it asks you for an email address, then they send you an email with a link to download it. You might have to register, it's so long ago I can't remember if I had to or not. Al

Do you have the EBL225 manual? Near the end is a wiring diagram, which tells you the fridge control board supply goes out through Pin 4. And all the other info you might need. I downloaded it from the Schaudt website. It's in German, but the manuals have English versions. You select the manual you want, it asks you for an email address, then they send you an email with a link to download it. You might have to register, it's so long ago I can't remember if I had to or not. All free.

I have the manual thanks and it appears to open a can of worms for me.
The wiring at the back of the panel does not appear to match the manual's layout, unless I am misunderstanding it?
Pin 4 on the wiring diagram is labelled "+ refrigerator control" on the wiring diagram.
Pin 4 on my panel is unused.
There was no 15A fuse in the "AES Only" fuse holder at top right. I have an AES fridge so I put one in and it does not appear to make any difference if it is in or out.
A couple of the other fuses were the wrong rating, so I replaced the lot with new, correct fuses.
I think I am going to have to double-check all the wiring at the back of the panel against the manual and test to make sure I know 100% what each cable is doing in real life.
Any ideas what is going on?

 

[Beryl]

When you test with the spare battery, where are you connecting it? Might be able to eliminate some of the possible cable runs/fuses to cut down the number to check.