My Caravan fridge wont work when towing

[Alf1]

Since 1997 I have owned an Audi 80 Tdi estste , a Passat Sport TDi estate car and a new Passat Trendline 100bhp Tdi estate, the last of the 05 models. I towed my Swift Charisma to Spain with all of these vehicles with no problem until I bought my new Passat, (the old shape model, I couldn't afford the new shape from my retirement fund!!!) The problem is as follows. The 12v fridge light flickers on and off and there is a clicking relay in the car and in the caravan. The fridge is not working when this happens. The tow bar and electrics were fitted by an approved fitter ( not VW's own). (I have had the car and the van checked out by various experts to no avail) I have had the electrics connected via the power outlets in the rear of the car, then a direct fused line from the battery and at this time the relay was replaced with a 30amp relay supplied by rydentowing. My alternator was relaced after 40.000 mls under warranty last October. Still the fridge is misbehaving, I have a full service history from my dealer for my caravan since 2001. Can you please shed some light on my problem, apparently the caravan centre tried a different vehicle attached to my van and the fridge worked. I know this is a problem that only exists when towing but it would be great to get back to the good alod days of having cool things from the fridge, 'en route,'

 

[BigAl1]

Alf.

There is a simple solution to your problem. What is happenning is that when the car supplies the fridge, the fridge operats for a second or so. This caused the car's battery Potential difference (or Voltage) to drop which tells the split relay to disconnect which results in the Voltage again rising which connects the relay and the fridge switched back on. The whole senario repeats.

You need to have your voltage sensed relay (in the car) replaced with one that operates when the ignition is on BUT NOT WHEN THE ENGINE IS CRANKING. From memory I think that is line 50.

Any decent auto-sparky will do this for you.

I speak from experience because I had the same situation with a Toyota Landcrusier and Fleetwood Heritage combination.

Hope this helps

Al

 

[Kitty1]

Alf

I don't know if you are having the same problem as I did but I was convinced my fridge wasn't working when connected to the car as the failure light flashed. Then someone advised that the fridge wouldn't work while the car was only idling, so I got moh to rev the engine while I checked the fridge and yeah! the fridge light stopped flashing indicating it was working normally. You're fault may not be as simple as mine was but I couldn't resist posting this just in case. Good luck.

Sophie

 

[Clive-Cardiff]

Hi Big Al.

Great to see your post as I have exactly the same problem with, guess what, Heritage and Landcruiser!!

In my case this relay problem is also causing problems with the alarm system,

I bought a new relay of the old type (not currnet sensing) and have been looking for where to plug into the ignition circuit. You quote line 50, where do I find this.

My Lancruiser is a D-4D LC4 2005. Any info apreciated

 

[alaintaylor]

Alf

This is a subject very close to my heart! I sweated over this for over a year by trying things each trip. I go to F1 and Le Mans races in Europe with a fridge full of weekend food plus G&Ts, ice and beers for arrival so a great reliance of the 12v system!

I've written quite a bit on another thread which is now near the top of this forum list - take a look. Seems a lot of people suffer this problem and it looks related to changing electrics technology in the tow car more than any other reason. Perhaps relay manufacturers are not keeping up?

Alan

 

[BigAl1]

Hi Big Al.

Great to see your post as I have exactly the same problem with, guess what, Heritage and Landcruiser!!

In my case this relay problem is also causing problems with the alarm system,

I bought a new relay of the old type (not currnet sensing) and have been looking for where to plug into the ignition circuit. You quote line 50, where do I find this.

My Lancruiser is a D-4D LC4 2005. Any info apreciated

Clive

I picked up the ignition/aux supply from the accessory socket located on the offside inner panel in the "bootspace".

Only downside is that when we have been parked up while waiting to board ferry and the kids were watching DVDs I remembered that the caravan fridge was also being fed because the split relay was also energised. But for a short time this was not a problem.

Caravan alarm....I know what is happenning, Because the relay has switched in and out so often, the alarm goes into "Valet mode" Your alarm handbook explains how to get out of this mode. Get back to me if you have probs with it.

Al

 

[Alf1]

Hi Alan

Thanks for your helpful suggestion

I understand your comments concerning power drop from the battery to the rear of the car. In fact my towbar fitter said I had less than 13.5 v with lights and climate control running, but he blamed this power loss on the fact that my Passat has climate control Even with climate switched off the frige red light still flickers on and off..

I did have a larger 30amp relay fitted and supplied by Ryden towoing No difference.

Can you explain the relay you mentioned and where one can be obtained?

 

[Clive-Cardiff]

Big Al,

Thanks for the info Big Al. I fitted the relay yesterday taking the ignition feed as you said from the accessory socket. All working OK.

I take your point about being parked up listening to the radio etc, probably not going to happen very often but something to watch out for.

As you said the alarm usually goes into valet mode with the rapid switching but the last time it happened I couldn't get it to reset. Tried disconnecting the leisure battery but no good.

I had to go through the full reset routine as per the book, straightforward but a bit of a podge having to take the microwave out to access the connections.

Thanks again for your help.

Alf,

I bought my relay from a local caravan dealers having looked through the Towsure catalogue and not found one. Mine was made by W4 and called a Combi Master relay, it cost about

 

[alaintaylor]

I'm out of circulation quite a bit at the moment, will forward info when I get home. Watch this thread!

Alan

 

[alaintaylor]

Hi Alf

Sorry for delay in getting back on this.

The relay I got was supplied direct from the manufacturer - Towing Electrics Limited who design and manufacture this sort of equipment. The unit is a 30amp TEC3M. Here follows there unit description:

"This combination caravan relay automatically senses battery/alternator condition and load

demand, and switches current from the car's battery to the caravan's battery, fridge and

internal lights via its own split charge relay. Sensing is automatic and does not require the

use of a separate lead from the ignition switch. Sensing takes account of over voltage

availability of the battery, demand condition from the caravan and line voltage drop under load

including the general condition of the connections train. The unit is very compact, which

belies its ability to handle large currents of up to 30 amps continuously through the use of

high quality low voltage drop relays and circuitry, whilst retaining an over temperature cut-out

capability.

The TEC3M has been constructed to not only handle 30 amp loads, but it will also handle

smaller loads from conventional caravans and still sense and process the load correctly."

The unit is slightly more expensive (

 

[Alf1]

Hi Alf

Sorry for delay in getting back on this.

The relay I got was supplied direct from the manufacturer - Towing Electrics Limited who design and manufacture this sort of equipment. The unit is a 30amp TEC3M. Here follows there unit description:

"This combination caravan relay automatically senses battery/alternator condition and load

demand, and switches current from the car's battery to the caravan's battery, fridge and

internal lights via its own split charge relay. Sensing is automatic and does not require the

use of a separate lead from the ignition switch. Sensing takes account of over voltage

availability of the battery, demand condition from the caravan and line voltage drop under load

including the general condition of the connections train. The unit is very compact, which

belies its ability to handle large currents of up to 30 amps continuously through the use of

high quality low voltage drop relays and circuitry, whilst retaining an over temperature cut-out

capability.

The TEC3M has been constructed to not only handle 30 amp loads, but it will also handle

smaller loads from conventional caravans and still sense and process the load correctly."

The unit is slightly more expensive (