jp11
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A friend is fitting new fridge to his 2012 Swift Escape. Can't figure out the wiring. Can anybody help?
Wiring new Thetford fridge to 2012 Escape (1 Viewer)
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What model of fridge is it? If it's new doesn't it have a wiring diagram with it?
For a 3-way fridge there's usually five wires. The high current supply (thick wires) often comes direct from the starter battery, or from the distribution box. That's for the heater element for the fridge to work on 12V when the engine is running.
There's a low current supply (thin wires) which powers the fridge control board, and all the necessary controls like the switching, the gas valve, ignition etc. This usually comes from the habitation battery, via the distribution box,
There will also be a 'D+' signal, that tells the control board when the engine is running, so it can switch to 12V.
The thick wires are easy to identify, the D+ is the one that is 12V when the engine is running, and off when not. The low current supply is the pair that's left.
For a 3-way fridge there's usually five wires. The high current supply (thick wires) often comes direct from the starter battery, or from the distribution box. That's for the heater element for the fridge to work on 12V when the engine is running.
There's a low current supply (thin wires) which powers the fridge control board, and all the necessary controls like the switching, the gas valve, ignition etc. This usually comes from the habitation battery, via the distribution box,
There will also be a 'D+' signal, that tells the control board when the engine is running, so it can switch to 12V.
The thick wires are easy to identify, the D+ is the one that is 12V when the engine is running, and off when not. The low current supply is the pair that's left.
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jp11
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Thanks for that. I think it was actually second hand, so no wiring diagram. That would have been too easy!
He bought the van privately, so he's not getting any help from local dealers.
I'm guessing the orange/white wires from the van are positives.
The thick one to the fridge red. The red/yellow one to white.
Maybe the brown/yellow is the D+ but we'll check for current with ignition on and off (or should that be "engine running" on and off?).
The other two orange/whites we'll just fiddle with.
He bought the van privately, so he's not getting any help from local dealers.
I'm guessing the orange/white wires from the van are positives.
The thick one to the fridge red. The red/yellow one to white.
Maybe the brown/yellow is the D+ but we'll check for current with ignition on and off (or should that be "engine running" on and off?).
The other two orange/whites we'll just fiddle with.
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Hope you're feeling lucky
I'd buy/borrow a multimeter if I were you, If you get the polarity wrong you'll ruin the control board.What model is it? This wiring is fairly standard, the diagram for this or a similar fridge should be available, I recognise the black/lilac/orange wiring but can't remember which is which. Orange for D+ if we're playing at guessing.
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jp11
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Not sure of the model, I'll have to get back to him.
I've found a wiring diagram for another Thetford and as you say the wiring will probably be similar.
Orange is d+
Purple is LC+
Black is LC-
That's looking like the van brown/yellow is LC-
And the two orange/whites are D+ and LC+ (to be checked with the meter).
I've found a wiring diagram for another Thetford and as you say the wiring will probably be similar.
Orange is d+
Purple is LC+
Black is LC-
That's looking like the van brown/yellow is LC-
And the two orange/whites are D+ and LC+ (to be checked with the meter).
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jp11
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Update. Autorouter was right not to play at guessing.
The brown/yellow is Positive (HC). The white/orange is Negative, three of them, one HC, two LC.
Then there is a brown/yellow LC. The wiring diagram says it is connected to P7, whatever that is.
There is no D+ wire, even thought there is a 10A fuse in the fuse box, marked D+ fridge.
I'd have thought there should be two LC wires: an LC power supply for the fridge electronics, and a D+ to let it know when to switch to battery.
The fridge loom has three LC leads: a black negative, a purple positive, and an orange D+.
The brown/yellow is Positive (HC). The white/orange is Negative, three of them, one HC, two LC.
Then there is a brown/yellow LC. The wiring diagram says it is connected to P7, whatever that is.
There is no D+ wire, even thought there is a 10A fuse in the fuse box, marked D+ fridge.
I'd have thought there should be two LC wires: an LC power supply for the fridge electronics, and a D+ to let it know when to switch to battery.
The fridge loom has three LC leads: a black negative, a purple positive, and an orange D+.
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Was the previous fridge a 3-way type, or was it a compressor type?
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- Aug 18, 2014
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I've never seen a fridge that didn't have the wiring diagram on the back?
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jp11
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I'm OK with the fridge wiring diagram.
HC positive and negative.
LC positive and negative.
D+
It's the van. It's missing D+ (even though there's a fuse in the place where it says D+ fridge).
But the other problem is that there's no power at the wire I think is LC positive.
All fuses are OK.
HC positive and negative.
LC positive and negative.
D+
It's the van. It's missing D+ (even though there's a fuse in the place where it says D+ fridge).
But the other problem is that there's no power at the wire I think is LC positive.
All fuses are OK.
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Does the van HC wiring (the thick wires) stay on all the time, or does it only come on when the engine is running? Maybe it's switched by a relay from the D+ before it reaches the fridge.
Also at the D+ fuse terminals, does the D+ signal reach the fuse terminal OK?
Also at the D+ fuse terminals, does the D+ signal reach the fuse terminal OK?
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If you have a Sargent PSU 460 unit fitted I think it is possible that you may find it has the D+ going to it via a Fiat connector and the unit controls the fridge operation and HC supply. (according to the Sargent Swift group schematics showing a 3 x way fridge)
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If your distribution box is a Sargent brand, the D+ connection and fuse will be in the wiring diagrams somewhere. Is it a Sargent, and if so what model number is it?
It's possible that the previous fridge was a simple manual type, and the HC wiring is controlled by a relay, for example in the Sargent box, so that the power was only switched on when the engine was running. It's something you could easily check. That would explain the absence of D+ signal wire to the fridge.
It's possible that the previous fridge was a simple manual type, and the HC wiring is controlled by a relay, for example in the Sargent box, so that the power was only switched on when the engine was running. It's something you could easily check. That would explain the absence of D+ signal wire to the fridge.
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I think once you have the LC wires connected, the fridge will work on both gas and 240V, when the gas and 240V connections are made. It probably still won't work on 12V, because I think the control board needs a D+ signal to tell it to switch to 12V.
If that's what happens, one possible thing to try - but I've never actually done this - is to connect the fridge D+ (orange) to the HC positive, because that is acting just like a D+: on when the engine is running, off when not.
If that's what happens, one possible thing to try - but I've never actually done this - is to connect the fridge D+ (orange) to the HC positive, because that is acting just like a D+: on when the engine is running, off when not.
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jp11
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Good point. It's just a signal. And would be sync'd.
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My friend has just connected up the LC+ with the D+ on the fridge loom. Result! It's working now on auto mode. He may have to keep an eye on his starter battery state of charge, but we'll see.
Can I just thank Autorouter and GeoffnDee so much for their input and advice. I've rarely seen such clear and friendly advice on any forum, of any kind, before. You're both a credit to the community.
Can I just thank Autorouter and GeoffnDee so much for their input and advice. I've rarely seen such clear and friendly advice on any forum, of any kind, before. You're both a credit to the community.
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- Jan 28, 2008
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If you need a dplus signal a smartcom relay set to trigger above13v can supply it from virtually any live wire in the van
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jp11
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Sorry Mitzimad. I'm no further forward. All the Smartcom relays I've searched for are split charge relays. I have a B2B charger that needs a trigger to tell it to start. I don't want a charging current going through the D+ terminal of my charger.
Forgive me if I sound stupid. I haven't even come to terms with what a D+ signal is. What is it? Does it provide a constant current? Is it some kind of tickling stick? Does it just send a ping?
Bloody Hell the world is full of jargon.
You see, your comment "If you need a dplus signal a smartcom relay set to trigger above13v can supply it from virtually any live wire in the van" doesn't really help me if I don't know exactly what to get and what to do with it.
Now, having said all that, I've finished a build to a very high standard. So I'm not stupid. Everything works very well. The B2B D+ terminal is currently (no pun intended) connected to a switched live in the fuse box, and everything seems to be fine. But after reading so many threads about what I should have done, I'm feeling uneasy. Right now, I'm waiting for a reply from Renogy to see if I've done anything wrong.
Forgive me if I sound stupid. I haven't even come to terms with what a D+ signal is. What is it? Does it provide a constant current? Is it some kind of tickling stick? Does it just send a ping?
Bloody Hell the world is full of jargon.
You see, your comment "If you need a dplus signal a smartcom relay set to trigger above13v can supply it from virtually any live wire in the van" doesn't really help me if I don't know exactly what to get and what to do with it.
Now, having said all that, I've finished a build to a very high standard. So I'm not stupid. Everything works very well. The B2B D+ terminal is currently (no pun intended) connected to a switched live in the fuse box, and everything seems to be fine. But after reading so many threads about what I should have done, I'm feeling uneasy. Right now, I'm waiting for a reply from Renogy to see if I've done anything wrong.
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The D+ signal is sent out by the alternator when it is running, and drops to zero when the alternator stops. It's called a signal because it is very low-power, and typically it is used as a trigger for various relays - the fridge relay, the split charge relay and in your case the B2B. It switches between about 12V and zero.
A relay is an electrically operated switch, where a small current goes through a coil, creates a magnetic field, which pulls two heavy-duty contacts together so that they touch. So for example the D+ signal (low power) can trigger a high power current for the fridge through the heavy-duty contacts.
Anything that is 12V when the engine is running, and zero when it stops, can be used to trigger the fridge and split charge relay. For example, a Smartcom voltage-sensitive relay switches on when the alternator/starter battery voltage is above a threshold, and switches off when the voltage drops below the threshold. This can be used as a substitute for a D+ signal. It can trigger the fridge, or a B2B. The D+ terminal of the B2B will take as much amps as it needs from the signal, ie very little.
It's worth looking to see if the D+ signal is available on the EC460 box. Remove the D+ fuse, and probe the fuse terminals with a meter, to see if it is actually about 12V with engine running, and about zero with engine stopped. One of them should do this, the other probably won't do anything.
If you get a good D+ signal there, it's worth investigating the wiring to see which wire the D+ comes out on. Then you could run a wire from there to whatever needs D+. Because it's a low-power signal, only a thin wire is needed.
A relay is an electrically operated switch, where a small current goes through a coil, creates a magnetic field, which pulls two heavy-duty contacts together so that they touch. So for example the D+ signal (low power) can trigger a high power current for the fridge through the heavy-duty contacts.
Anything that is 12V when the engine is running, and zero when it stops, can be used to trigger the fridge and split charge relay. For example, a Smartcom voltage-sensitive relay switches on when the alternator/starter battery voltage is above a threshold, and switches off when the voltage drops below the threshold. This can be used as a substitute for a D+ signal. It can trigger the fridge, or a B2B. The D+ terminal of the B2B will take as much amps as it needs from the signal, ie very little.
It's worth looking to see if the D+ signal is available on the EC460 box. Remove the D+ fuse, and probe the fuse terminals with a meter, to see if it is actually about 12V with engine running, and about zero with engine stopped. One of them should do this, the other probably won't do anything.
If you get a good D+ signal there, it's worth investigating the wiring to see which wire the D+ comes out on. Then you could run a wire from there to whatever needs D+. Because it's a low-power signal, only a thin wire is needed.
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