Clicking relay and CBE box

[andrey55]

Hi,

We have a Chausson from 2002 and have lately have some clicking noise from a relay that is next to the CBE distributions box. The clicking sound appears only when the engine is running, when we press the gas pedal the clicking sound dissapears.

We had 2 batteries for the living area before but i needed to change them becouse they were dead. I removed them and replace it with just one new one. After that the clicking started.

Could it be something with the alternator or maybe the car needs to have 2 batteries for the living area?

Anyone has any clue?

Best regards,
Andrey

 

[Landy Andy]

It could be a voltage sensing relay, so is at an unstable voltage so is clicking in and out.

A photo of the relay would help.

 

[andrey55]

It could be a voltage sensing relay, so is at an unstable voltage so is clicking in and out.

A photo of the relay would help.

Does this photo helps anything?

Well it could be becouse the clicking sound changed due the acceleration.

 

[herald_400rl]

What voltage do you get to the bottom pins when the engine is idling? And what do you get across your ignition battery when idling and then under load?

 

[andrey55]

What voltage do you get to the bottom pins when the engine is idling? And what do you get across your ignition battery when idling and then under load?

I have not messure it yet. I have 4 pins, which of thoose do i need to messure?

It is 2 thick cables (red and brown) and 2 smaller cables that is blue and black.

I may also have a diagram somewhere if that is something that can help.

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[herald_400rl]

The thicker cables, one will be supply from the alternator/van battery depending on your charging setup the other going to your leisure battery and the smaller ones will be for a switches live which will make the relay live, a small current goes through the relay which activates it (an electromagnetic switch).

What you might find is the relay is nackered if the supply voltages are constant, a new relay can be had for less than 20 quid and is a relatively simple DIY swap.

 

[andrey55]

The thicker cables, one will be supply from the alternator/van battery depending on your charging setup the other going to your leisure battery and the smaller ones will be for a switches live which will make the relay live, a small current goes through the relay which activates it (an electromagnetic switch).

What you might find is the relay is nackered if the supply voltages are constant, a new relay can be had for less than 20 quid and is a relatively simple DIY swap.

Funny thing is that the relay was the first thing i changed.. But the issue is still there.

I will messure the alternator. Could be that one. If not, i will maybe need to check all ground wires, i read somewhere that it could also be that. What do you think?

 

[herald_400rl]

It could be a degraded negative/ground wire somewhere but that will be a hunt...

 

[dunnah01]

You need to measure the voltage at pin 85 when idling and then when revving. If different the CBE panel probably has a built in voltage sensing relay that is triggering this external relay to charge the leisure battery above a certain voltage. Unless it is rapidly clicking on/off all the time I wouldn't worry too much about it although your starter battery may be showing it's age and asking for more oomph at idle than the alternator can provide. Are any higher power accessories switched on when idling which may also be sapping current at low revs?

 

[Pausim]

Relays that operate when the engine is running are usually triggered by a D+ signal from the alternator. It is possible that it is this signal that is failing to get through to your relay properly. Some CBE units take the D+ signal and use it to trigger/create a simulated D+ signal, this avoids overloading the original D+ signal. All this involves relays and wiring and if there is too much voltage drop along the way the relays can drop in and out. Revving the engine possibly raises the voltage sufficiently to hold the relay.

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[autorouter]

It is 2 thick cables (red and brown) and 2 smaller cables that is blue and black.

That's not a voltage-sensitive relay, it's a standard on/off relay. It should switch on if the voltage on the smaller cables is anything over about 8 or 9 volts.

The signal to the smaller cables might come from the D+ signal from the alternator. It is a 'signal' rather than a power supply, which means it can only supply a very small current. Originally it was only used to switch off the alternator light on the dashboard when the alternator was up and running. In a motorhome it's used for all kinds of things - connecting leisure battery to starter battery, turning the fridge to 12V, retracting the step, cutting off the awning light, and many other things. If you try to take more than a tiny current from the D+, its voltage sags, especially if the alternator is not spinning very fast.

One solution is to get the D+ signal to trigger only a single relay, it should be able to do that without difficulty. Then use the power terminals to trigger all the other devices that need to be switched when the engine starts. That's usually called a D+ Simulator. As Pausim says, there is one of these built into the CBE box.

If that relay is clicking, but the other relays like the fridge and awning light are not, maybe it is wired to the original D+, not the D+ simulator, and it's overloading the real D+ a bit when the engine is idling, causing the clicking.

 

[andrey55]

It could be a degraded negative/ground wire somewhere but that will be a hunt...

I will need to check that.

 

[andrey55]

You need to measure the voltage at pin 85 when idling and then when revving. If different the CBE panel probably has a built in voltage sensing relay that is triggering this external relay to charge the leisure battery above a certain voltage. Unless it is rapidly clicking on/off all the time I wouldn't worry too much about it although your starter battery may be showing it's age and asking for more oomph at idle than the alternator can provide. Are any higher power accessories switched on when idling which may also be sapping current at low revs?

Thank you i will do that.

I will also try a newew battery to see if the clicking stops.

No higher accesories is on when idling. I have also tried to disconnect the lessiure battery and it is still clicking.

The clicking sound is very rapidly and it is loud.

 

[andrey55]

Relays that operate when the engine is running are usually triggered by a D+ signal from the alternator. It is possible that it is this signal that is failing to get through to your relay properly. Some CBE units take the D+ signal and use it to trigger/create a simulated D+ signal, this avoids overloading the original D+ signal. All this involves relays and wiring and if there is too much voltage drop along the way the relays can drop in and out. Revving the engine possibly raises the voltage sufficiently to hold the relay.

Ok, so it could maybe be the alternator that is giving to much voltage? I will messure the alternator voltage today and see if we have a problem there.

 

[andrey55]

That's not a voltage-sensitive relay, it's a standard on/off relay. It should switch on if the voltage on the smaller cables is anything over about 8 or 9 volts.

The signal to the smaller cables might come from the D+ signal from the alternator. It is a 'signal' rather than a power supply, which means it can only supply a very small current. Originally it was only used to switch off the alternator light on the dashboard when the alternator was up and running. In a motorhome it's used for all kinds of things - connecting leisure battery to starter battery, turning the fridge to 12V, retracting the step, cutting off the awning light, and many other things. If you try to take more than a tiny current from the D+, its voltage sags, especially if the alternator is not spinning very fast.

One solution is to get the D+ signal to trigger only a single relay, it should be able to do that without difficulty. Then use the power terminals to trigger all the other devices that need to be switched when the engine starts. That's usually called a D+ Simulator. As Pausim says, there is one of these built into the CBE box.

If that relay is clicking, but the other relays like the fridge and awning light are not, maybe it is wired to the original D+, not the D+ simulator, and it's overloading the real D+ a bit when the engine is idling, causing the clicking.

Thank you!

I think that the relay is also connected to the fridge. Maybe it could be some issues with the fridge also?

The soultion you mention about a single relay. How should i do that? Will everything works like it should after that also?

I will attach the diagram that i found. Maybe it will help.

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[TheBig1]

It could be as simple as a tired relay that needs replacing for about £2

 

[andrey55]

It could be as simple as a tired relay that needs replacing for about £2

Relay is alredy changed without success.

 

[dunnah01]

The diagram shows the relay is directly triggered by the alternator output. There should be 14.4v at pin 86 with the engine running so if it is a lot less or zero then your alternator may be acting up

 

[Pausim]

From the diagram I can see a D+ signal wire from the alternator but not the alternator output connection. The D+ originates from the field windings and might not show the same voltage as the alternator output.

 

[autorouter]

The basic reason that the relay is clicking is that the voltage when the relay is on is not enough to hold it on, so the relay switches off. For example, the D+ signal voltage is high enough to switch the relay on.

When the relay switches on, the power to the devices it switches on might be quite high, so the alternator voltage might drop, and also the D+ voltage might drop as well. If the alternator is not producing much power, when idling for example, then the voltage drop on the D+ signal might be so bad that the relay switches off.

At that point the devices switch off, there is less load on the alternator, so the voltage recovers again, and the D+ signal recovers enough to turn on the relay again. And so on, causing the clicking on and off.

The question is, what is causing all this? Usually it's a 'tired' relay, but there's other possibilities. Bad connection in the wiring somewhere causing a resistance and a voltage drop, for a start. Bad connection on the earth side, as already mentioned. It could even be a faulty alternator.

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[Sandancers]

Our chausson developed the exact same problem. It turned out to be a thin black wire going into the negative battery terminal connector was not crimped in tight enough.

I had disturbed the wire by moving it to screw something to the seat base.

Made good the connection and solved it.