missing relay

[pug306driver]

I have the car in bits at the moment, front brakes now done but chassis rail top be painted.

The ecu and its boxes are off the body and to one side, and I have found the electric cooling system heater plugs, which didn't seem to work as the car took a few miles to warm up to temp.

The black box mounted on the ecu frame has a relay missing, ie not fitted.

Its the relay on the inner end of the black box, engine end, what does this control please??

Also what do the other relays control in this black box??

I know the large brown double relay is to do with fuel?

Thanks in advance for your help.

I can post some pictures if needed.

[DeeTurbo]

The two relays in the black box control the heater plugs and they work in two stages. At the lowest temperatures both pairs come on then only one pair.

It's worth doing a resistance check on the heater plugs as most have now mostly likely failed.

The brown relay has two relays inside and it controls the fuel pump and the the power to the ecu as well.

[Magenta Sunset]

anyone got a pic of this? something i'd like to check too - -

[DeeTurbo]

What do you need a pic of?

[Magenta Sunset]

the black box preheater relay please

[pug306driver]

Thank you thank you thank you, there are 3 green relays in that black box at the moment, will remove each in turn and check for burning contacts, bad contacts, outside of the relays.

Will try and sus what contact is what and check relays, clicking, switching, using the Haynes manual wiring diagram, but a pug diagram for this system 1999/2000 ph3 2 liter hdi turbo estate would be super.

So the missing relay, closest to the engine end of the black box, is to do with the coolant heaters??  The missing relay should also be a green one ( same as the others ) ??

Will check on coolant heater plugs for resistance value.

I can take a picture and post on Monday as no internet at home.

Could someone post the pug part number for this/these relays please, as well as the pug wiring diagram for this system, pretty please

Little confused, are all 4 relays to do with the coolant heater system, as 2 pairs of relays are mentioned in first answer.

[DeeTurbo]

The entire contents of the black box is the control relay system for the heater plugs and I think the engine glow plugs to.

I'll get some photos of one when I get home.

[Toms306]

The engine plugs use that massive black relay with the green bottom I think?

[DeeTurbo]

This is the relays for the coolant heater plugs. As you can see from the photo there are only meant to be two relays. One per pair of heater plugs.



This is the relay for the engine glow plugs. It's usually this going faulty that causes the glow plug fault code.

[pug306driver]

That's the one, the coolant heater plugs relay board, 2 relays and 2 fuses, one relay and fuse for each pair of coolant heater plugs, 2 pairs of 2 coolant heater plugs, each pair wired in parallel and independent of the other pair, and earthed thru the alloy uni9t and bracket to the engine.

There must be some buss bars in the board to connect the relays to the energizer wires, which seem to be mainly grouped at one end of the board.

The thick white wire goes to one pair of plugs and the thick brown wire to the other pair.

One pair comes on at a low temp and the other pair then comes on for a lower temp??

Both pairs of plugs showed 15ish ohm ( 14, 15 ohms ) but the relay closest to the engine has some heat damage ( the power feed to the plugs shows some overheating, spade blades sticks out a bit )  and the female terminal  in the board shows some plastic deformation due to heat  .

I assume this "circuit" is the low temp circuit which would come on more often?

Will clarify which wire ( white or brown ) and which set of plugs.

Does the ecu get feedback that the set of coolant heater plugs relay is "on" as there is one small wire coming from the engine end relay area, the brown wired power feed to the plugs area?  or may be a warning light that the coolant heater plug system is "on or working" ?

It could be that relays energizer wire?

The black and green box with blue writing is the relay for the engine heater plugs.

[DeeTurbo]

The thin wire comes from the ECU as it's what controls when the plugs come on. I thought the pugs were supposed to be around 1ohm? I'll check mine tonight.