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woop

14CUX Main and Fuel pump relay operation

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Hi all, Im currently transplanting a Disco 2 Underbonnet fusebox into my '93 3.9 Disco 1 in an effort to neaten up the wiring with its associated mass of relays scattered inside the car. Ive studied the 14CUX wiring diagram, but could someone here confirm that the ECU supplies grounds on pin 12 for the Main Relay and Pin 16 for the Fuel pump relay to enable operation.

cheers

Nick

 

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My 3.5 EFI diagram shows the same connections. The 3.9 is similar.

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I've a feeling that one of them grounds the pin and the other actually supplies 12v.... quick check...

Flapper diagram looks like a positive feed from the ECU with a common ground.

Hotwire both wires to the relay go back to the ECU, by the diode inline with the coil it looks like White/Slate wire supplies +12v, Blue/Purple is GND, but no word on which is switched.

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Isn't there a tie-in with an oil pressure switch, too?

I may be way off base, but there is a lingering fragment of a thought along those lines. Something to do with the pump continuing to run after the initial prime when the engine has started.

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No, although there was a relay connected to a vacuum switch which cut off the pulses from the coil on over-run to save fuel on the Flapper, plus the red "relay" which contains a few diodes they forgot to put inside the ECU :rolleyes:

Flapper diagram:

lucas_efi_1982_1984.jpg

 

Hotwire diagram:

lucas_efi_1988_1989.jpg

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Thanks for the replies-I looked at the D1 14CUX diagram for the version without the combined main/fuel pump relay module, and i think I can safely say it switches them to ground.....Im guessing Fridge that this is why relays both contain Flyback diodes? 

Cheers

Nick

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10 hours ago, JohnnoK said:

Isn't there a tie-in with an oil pressure switch, too?

I may be way off base, but there is a lingering fragment of a thought along those lines. Something to do with the pump continuing to run after the initial prime when the engine has started.

U are not way off, but the only connection to the pressure switch is the dash lamp illumination.

After the pump has primed it stops, it restarts as soon as the engine is running, switched by the ECU when pulses are given from the ignition coil to the ECU.

The fuel pump and EFI/Main relays (AFU 2913L) are expensive new, so don’t break them, they are the only two of that type fitted. Also the D1 EFI engine is “hot wire” it always has been so don’t confuse it with the Range Rover 3.5 “flapper “ engine.

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@teabag - Those expensive relays are easily re-created with regular bits though, no rocket surgery in them.

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Thanks for the info guys Ive decided to go the whole hog and transplant the D2 BCU and Fusebox... Ive assembled everything on the bench and made everything work except the Heated Rear Window which it looks like the BCU is looking for an Engine Running Signal from the Cluster. Ive tried simulating oil pressure and an Alternator output without any success. What does the Cluster use as an Engine Running signal?

 

Cheers

Nick

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15 hours ago, woop said:

except the Heated Rear Window which it looks like the BCU is looking for an Engine Running Signal from the Cluster

Where did you get that info from cos it's not true, the HRW operation has nothing to do with that signal which i dont even understand what it is

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19 hours ago, woop said:

Thanks for the info guys Ive decided to go the whole hog and transplant the D2 BCU and Fusebox... Ive assembled everything on the bench and made everything work except the Heated Rear Window which it looks like the BCU is looking for an Engine Running Signal from the Cluster. Ive tried simulating oil pressure and an Alternator output without any success. What does the Cluster use as an Engine Running signal?

 

Cheers

Nick

Hi Nick

As I’m sure you know, that’s a very good safety function, that the D1 has for the rear heated screen. 

The front heated screen also has the same feature, both are control by the D1s multifunction unit which also gives the heating time duration function for the two screens. 

So I suspect that the D2 doesn’t have that feature.

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7 hours ago, sierrafery said:

Where did you get that info from cos it's not true, the HRW operation has nothing to do with that signal which i dont even understand what it is

I found that information whilst reading the HRW operation description from the Disco2 Electrical Library-It states the HRW will only operate with the engine running because of the high current draw and that the BCU looks for a signal from the Cluster via the Comms Bus that the engine is running. Ive assembled a matching BCU,FuseBox and Cluster together to test on the bench and so far this is the only thing that Ive been unable to make work. Ive tried using the oil pressure lamp and Alternator charge lamp inputs without any luck to simulate the engine running signal 

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Would it not be battery-voltage based like the old voltage-sensitive switch in RRC's and D1's?

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2 hours ago, woop said:

I found that information whilst reading the HRW operation description from the Disco2 Electrical Library-It states the HRW will only operate with the engine running because of the high current draw and that the BCU looks for a signal from the Cluster via the Comms Bus that the engine is running. Ive assembled a matching BCU,FuseBox and Cluster together to test on the bench and so far this is the only thing that Ive been unable to make work. Ive tried using the oil pressure lamp and Alternator charge lamp inputs without any luck to simulate the engine running signal 

I've read the description of HRW few times and i missed that part but i' checked again and i see where are you coming from, sorry that i contradicted you  even though IMO the description is not 100% accurate if it's corroborated with the circuit diagram cos the signal from the IC spilices into the serial data bus from C0233-16 which is not particulary an engine speed signal but maybe it is within the digital input so if you wired them all together with all the inputs you need an engine speed input into the cluster as the tachometer to show you idle and that's a digital 2 pulse/rev signal which is coming from the ECM black plug pin 19 into IC connector C0230 - 15

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On ‎1‎/‎17‎/‎2019 at 2:10 AM, sierrafery said:

I've read the description of HRW few times and i missed that part but i' checked again and i see where are you coming from, sorry that i contradicted you  even though IMO the description is not 100% accurate if it's corroborated with the circuit diagram cos the signal from the IC spilices into the serial data bus from C0233-16 which is not particulary an engine speed signal but maybe it is within the digital input so if you wired them all together with all the inputs you need an engine speed input into the cluster as the tachometer to show you idle and that's a digital 2 pulse/rev signal which is coming from the ECM black plug pin 19 into IC connector C0230 - 15

That's ok no problem :) Ive looked again at the wiring diagrams, and I'm going to try and simulate an engine running signal by enabling the Main Relay-something I hadn't tried before. If this dosent work, I'll use the unused Heated Front screen relay and just connect it to my original timer module

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8 hours ago, woop said:

That's ok no problem :) Ive looked again at the wiring diagrams, and I'm going to try and simulate an engine running signal by enabling the Main Relay-something I hadn't tried before. If this dosent work, I'll use the unused Heated Front screen relay and just connect it to my original timer module

So it looks if you have the EFI system up and running, so great, but now your concerns are the operation of a heated rear screen.

Why not go back in time when such items were  switched on with a dash switch, plus a lamp with a colour of your choice which was illuminated when ON,  Is that not  a simples way of achieving your objective.

Plus if you feel that u won’t see the lamp illumination, move on a couple of years in time and interface a “timer” relay into the ignition supply circuit... Simples 😊

 

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On 1/19/2019 at 9:37 AM, teabag said:

So it looks if you have the EFI system up and running, so great, but now your concerns are the operation of a heated rear screen.

Why not go back in time when such items were  switched on with a dash switch, plus a lamp with a colour of your choice which was illuminated when ON,  Is that not  a simples way of achieving your objective.

Plus if you feel that u won’t see the lamp illumination, move on a couple of years in time and interface a “timer” relay into the ignition supply circuit... Simples 😊

 

I ended up reusing the original Heated Rear window timer module and just connecting it to the ground side of the unused Heated Front Screen relay coil in the Disco 2 Fusebox. Trying to Access to Heated Rear Window relay coil in the Disco2 Interior fuse was difficult due to it being tied in to the IDM. It seems to work ok using this method. For the EFI, made my own engine harness with the original wiring colors, and connected it to the Disco2 Fusebox to allow control of Fuel Pump and Main Relays. I reused the original Fan Timer module on the ground side of the Disco 2 Fan Relay. All in all its been a fiddly and time consuming job, but along the way, Ive learnt a lot about the Disco 2 electrics :)

Edited by woop
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Well done @woop
 most people shy away from that sort of thing

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