The V8 Owners Forum -

After finding out the Range rover classic won't start due to no fuel (think its power to pump) i was adviced to check the negative wire on coil that runs to tach/ecu but I'm not 100% its working right?.

The wire i have has 12volt coming out of the coil which runs into a resistor but there is no voltage whatsoever coming out of the resistor (ignition on)? Does this sound right im pressuming there should be battery voltage comming out?

Second question where can i get the right resistor if i need to

Cheers for any help as a newby im off to trawl the site

Hi Danny,

Dannyb wrote:
The wire i have has 12volt coming out of the coil which runs into a resistor but there is no voltage whatsoever coming out of the resistor (ignition on)? Does this sound right im pressuming there should be battery voltage comming out?

If you RR setup is smilar to the SD1 then this will explain.

http://www.vintagemodelairplane.com/pag ... ger01.html

There is no reason to believe that its broken because the voltage is Zero, it could just be connected to a low input resistance (impedance) in the ECU which deals with the pulses from the coil when engine running.

Second question where can i get the right resistor if i need to.

The resistor is VERY unlikely to fail but if it is open circuit then a RR dealership or a RR Breaker would be a good bet.

If you need flapper circuits, circa 1985, they will be similar to the ones found in this index.

http://www.vintagemodelairplane.com/pag ... er_dl.html

Thanks its the same system as the SD1 (same resistor) range rover manual says it should have 12v in and 12v out so im guessing its bust : Also its the wire that tells ecu to switch pump on( Hopefully engine will start when this is fixed.

If it's in the wire to the ECU, then it goes into a very high impedance input, so you should see the same voltage on both sides of the resistor.

A simple test would be just to connect the two wires together that go on each end of the resistor and see if it starts then.

Alternatively you could measure the resistance of the resistor with an ohm-meter. I forget what it is, but I think it's on Ramons site.

Chris.

Cheers:) There is definatly no voltage out and there is batter voltage between coil and resistor, I take it from what i read on these forums its safe to remove it (seen post were people have done this) and get it replaced as soon as i get my hands on a replacement.

I run without one, and have dismantled the ECU to convince myself that it won't affect the functionality.

Other people have different opinions on this.

Chris.

Cheers will try it tomorrow night

Still wont run no power to fuel mump relay and maybe ecu relay an pointer what to check?

Checked everything as per manual checked earthing pin 16 no voltage there at all which = Dead ECU according to manual

need to find ECU know

They come up on eBay quite often, or you might be able to borrow one if you're near somebody with a spare.... (I have a couple of spares if you're near me).

Chris.

Dannyb wrote:Still wont run no power to fuel mump relay and maybe ecu relay an pointer what to check?

Danny, It sounds like the efi steering module might be worth checking.

http://www.vintagemodelairplane.com/pag ... ule01.html

Also there are other components which may prevent the ECU firing up or the main and Fuel pump relay from working - or the relays themselves or the sockets they connect to.

cheers for all the help

I work away all week so a freind is trying to sort it for me (technically still his car), will try steering module if the rr classic has one? The car was idling fine then it just stopped and refused to start since. It drove fine too only problem on entire car was rev counter had a mind of its own

with my ecu no power to fuel pump relay
with borrowed ecu power to fuel pump relay

Still no start no priming of pump connected live straight to fuel pump and its dead, Also wire from coil is 12v upto resistor still nothing coming out for ecu signal.

How can it go from running sweet to having knackered pump , resistor and ecu???

Dannyb wrote:cheers for all the help

I work away all week so a freind is trying to sort it for me (technically still his car), will try steering module if the rr classic has one? The car was idling fine then it just stopped and refused to start since. It drove fine too only problem on entire car was rev counter had a mind of its own

Danny, the tacho uses the negative side of the coil for its engine speed input signal along with the same take-off point for the ECU trigger resistor/signal you referred to in your opening post.

This circuit shows the component #452 trigger resistor and you can see the WB wire that goes to the Tacho #95 from one side of that resistor.

http://www.vintagemodelairplane.com/pag ... uit01.html

If the tacho had been playing up, its possible that there is a wiring problem around the connections to the negative side of the coil.

Also you might wish to recheck that the resistor is 6800 ohms and is securely connected between pin 1 of the ECU and the negative side of the coil. That very hot area of the engine bay is hostile to efi wiring.

Might be worth a look.

The next thing I am not clear about so this is speculation: If the trigger resistor had previously been omitted, then that means pin 1 of the ECU and the input to the Tacho are joined together.

That is not as per the original design so a faulty Tacho might be responsible for hurting the ECU or Vice Versa.

Either way there is a common thread to these two faults as you describe them.

The common factor might be the alternator playing up.