Blowing fuse 37

[manyhavetried]

Hi all, I'm new here and firstly would like to thank all kind folk for these invaluable forums. I've had my RR 4.6 '98 for 6 months now and all had been fine, ahh ignorance is bliss! So a about a month ago the engine cuts out and wont start, electrics work, no crank. A blown fuse 37 seemed to be the problem, all was well for 24hrs until the same thing happened again. Sent it to a stealer who said he had no clue what was wrong with her and i should junk it! Wan*er! This is where i began the glorious journey of being a proper LR owner! Fuse 37 was now blowing everytime the ignition was turned to position 2?? thanks to forums and the internet i came to the conclusion it was a duff fuse box. Replaced the fuse box and she started first time no warning lights! HAPPY DAYS... if only...

Since then fuse 37 has blown 5 or 6 times, mostly on 'warm' starts on hot days. I've also had engine overheating problems starting around the same time, I have to drive slowly and with the heater on to avoid gauge going red. Today, after checking earthing points around the engine compartment and a couple of looms, she decided to leave me stranded, again. Now back to every time ignition in position 2 instantly blows fuse 37. ARGGGHHHH

As far as i can figure Fuse 37 protects the Main Relay (R19) which, From RAVE: "supplies the power feed to the ECM and also the fuel injectors and air flow meter." From taking my old fusbox apart i make out : Relay 18 draws power from relay 19 but i know it's not that as ive taken it out and it still pops. So the only other thing linked to it is the ECM, ive traced it to C509 pin17 (Main Control Relay, output, voltage=switched to ground, page 350 in Wkshop Manual) but don't know what it does or goes after that. Page 23 of ETM for RR 1997 Shows the circuit diagram, but it may aswell be written in chinese!

Can anybody tell me what pg23 says?
Where does the power go to after entering ECM?
I also have a 'soft' EAS fault, Engine overheating, condenser fans not coming on, AC leak and a smashed tail light... Could any of these be connected to the same fault? or just a dream?

Thanks in advance

PS sorry for the long winded story

[manyhavetried]

FOUND THE MOTHER! Problem is solved, managed to trace the fault to a bad earth on one of the fuel injectors!

For anyone who might have the same fault in future here is how i found and corrected the problem:

Persistence in reading the ETM showed the relay was supplying the 8 FEUL INJECTORS and the air flow meter. The workshop manual also states this in plain english, as i'd written down here before, but the circuit drawings had me confused not able to see what was right in front of me!

So to testing, Firstly i pulled all 8 connectors for each injector (located above each cylinder) and tried starting, the fuse blew, so it was not a fault with the injectors themselves.

Then referencing the ETM and Workshop manual to trace each injector connector to the appropriate pin on the other end (ECM), Using a multimeter to test the resistance between the output pin (from ECM) to each of the two pins at the injector end. This was repeated for each of the 8 injectors. I found that all the readings were near identical except one injector would read 150 ohms on the ground pin (compared to the other ones not registering a value)

I could see that cable went to one of either two earthing points, I had previously moved all the cables from one of those points to another one after snapping the thread, and knew it was a now good connection, so it had to be the one (under fuse box behind ECM housing nearest to RH wing) I cut and extended the cable to another earth point and tested the resistance, it read like all the others.

Plugged all the connectors back in, put a new fuse in and gave it a go. Bingo!!!!!!!!!!!!!!!!

I have no previous auto mechanical knowledge (at all) so please only take this as reference to my experience. I only hope this helps somebody someday.

[manyhavetried]

Oh yea and thanks for all the help fellas!

[manyhavetried]

Update: It was not a 'Bad Earth' connection. As this wouldn't cause the fuse to blow. I found 150 ohms resistence accross the two pins at the connector (input and ground) So this proves there is a short. Poking a harness around i noticed a spark, so, disconected the battery negative and unwrapped the harness. I found two wires had been burnt and the copper exposed, presumably by heat from the engine. The colours matched input and ground from injector 2 but, to make sure, i tested for continuity by measuring for resistence at the exposed copper and corresponding pin. Then simply cut the wires and reconnected using a crimp on barrel connector.

It's been driving great all day, still haven't got used to it!
PS I LOVE MY RANGE ROVER


Photos for those interested: