Fuel pump relays?????
Discussion
I know there is a main relay and fuel pump relay in the ECU loom, so why is there another one fuel pump relay(according to the handbook) in the fuse box?
It also shows fuel pump feed fuse< I thought this was in the ECU loom also?
I thought the fuel pump feed came off the main relay on the ECU loom??
It also shows fuel pump feed fuse< I thought this was in the ECU loom also?
I thought the fuel pump feed came off the main relay on the ECU loom??
Edited by antonyj on Saturday 16th December 15:39
Edited by antonyj on Saturday 16th December 15:44
No idea what the "fuel pump relay" in the fuse panel is. The fuel pump relay is normally one of the two metal cased Bosch relays on flying leads on the ECU loom (the other is the main power relay). There will normally be a fuse for the power circuit in the fuse panel. You might find there's also a fuse for the control circuit (i.e. the one that actuates the relay) although from memory mine was unfused.
Mine has the relay and fuse in the fuse box too, Ant. At a guess it's the result of mating the Audi/VW fusebox to the Range Rover ECU/fuel pump wiring loom. ie not necessary, but more bother than TVR deemed it to be worth to remove.
The fuel pump wiring is a bit obscure. After several hours in the footwell with a multimeter, I figured it out. From memory the 12v supply to the ECU and fuel pump relays is permanent (and fused by the fuses in the loom). The 'controlling' 12v feed is ignition switched (and my be what is fed by the relay and fuse in the fuse box). However the fuel pump is actually controlled, by switching the 'earth' of the metal relay in the loom at the ECU. This is how the ECU powers the relay for 5 secs at ignition on, then permanently when the engine is running. Fascinating eh?!
The fuel pump wiring is a bit obscure. After several hours in the footwell with a multimeter, I figured it out. From memory the 12v supply to the ECU and fuel pump relays is permanent (and fused by the fuses in the loom). The 'controlling' 12v feed is ignition switched (and my be what is fed by the relay and fuse in the fuse box). However the fuel pump is actually controlled, by switching the 'earth' of the metal relay in the loom at the ECU. This is how the ECU powers the relay for 5 secs at ignition on, then permanently when the engine is running. Fascinating eh?!
Ben, I got that too, from the link you posted with all the RR ecu wiring.
Also I have just pulled apart a RR loom I bought for investigation.Sad I know.
Think you are probably right about the relay in the fuse box, just redundant, but typical tvr its on the relay diagram in the handbook.
Just been out to the car, removed the relay in the fuse box, and the pump doesnt run without it...........
Both relays in the ecu loom are switched on the negatives by the ECU. The ecu gets an ignition key switched supply and then switches both the main and fuel pump relay.
I guess the FP relay in the fuse box is just switched with the iginition.
Also I have just pulled apart a RR loom I bought for investigation.Sad I know.
Think you are probably right about the relay in the fuse box, just redundant, but typical tvr its on the relay diagram in the handbook.
Just been out to the car, removed the relay in the fuse box, and the pump doesnt run without it...........
Both relays in the ecu loom are switched on the negatives by the ECU. The ecu gets an ignition key switched supply and then switches both the main and fuel pump relay.
I guess the FP relay in the fuse box is just switched with the iginition.
Edited by antonyj on Monday 18th December 13:27
Gassing Station | Griffith | Top of Page | What's New | My Stuff