yes ffrr14. I have a nice length of cable I intend to terminate (under car) on top of the actuator terminal on the starter, and run up to the battery, with a croc clip, ready for the inevitable return of the annoyance. -I would be able to jump out, and touch the clip to positive, and get the starter spinning, with the ignition on..... hoping there's enough diesel pressure etc.... I assume you leave ignition on, and touch wire, for the spin up, and it runs, -yes?

That will be a quick and dirty should the car fail to crank or to prove the hypothesis, Grame's solution is more elegant once this proves to be a permanent solution. SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

ffrr14 wrote:

What is a good brand setup you would recommend? also where did you pick up the signal?

Thats what I was thinking also, did you splice near the air box or further downstream? any pics?

I had the issue again after a long drive, appears the engagement is sluggish when engine is hot even with full SOC.

It can either be mechanical at the starter or there is voltage drop caused by thermal deg/expansion... hmm

clearly is a design issue SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

Last edited by ffrr14 on 10th Feb 2022 6:58pm. Edited 1 time in total

In Australia we were doing this in the 1960s to English cars, lucas them days. RR 2005 4.4 petrol
Any spelling mistakes are the fault of spellchecker
Previous MG J2, CITROEN light 15 x 2 gone unfortunately
Present MERC 180e, RANGE ROVER L322, JAGUAR XJS, MERC 280SE, MG F, JAGUAR S-Type 6v 2003, jaguar s-type 8v 2004, Ford Cougar

I just took the trigger wire off the solenoid and used it to trigger the small relay, which also needs an earth wire. The original trigger wire is more than adequate for the small current required for the relay.

Thanks for that, how is it working for you? SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

Mine's starter wasn't misbehaving but now seems quicker at jumping to life. The task was to save the solenoid contacts burning from inadequate engagement speed and engaged pressure before the contacts deteriorated much more.

good call! SOLD | Tuned MY 2011.5 Range Rover Autobiography 4.4 TDV8 Orkney Grey | e-diff | ACC

New Toy: Unimog U1550L/37
New : G350D

Graeme, I’m going to do this mod using the same style of motorcycle relay as you. However, whilst I get my head around the wire lengths and connections I need to purchase for the install, I’d be really grateful of any advice you can offer on the following:

- can you take the 12V battery feed to trigger the starter solenoid from the same 12V that feeds the main starter motor, or is it better to run an independent cable back to battery or the fuse box above? I assume that, as the motorcycle relay will open once you take your finger off the ignition button that there’s no reason why I can’t piggy-back the big fat 12V cable going to the motor as the connection will only be live whilst it’s triggering?
- what was the logic in installing the relay down near the starter? I’m thinking of putting it next to or in the fuze box at the top of the engine for easy access in the event of needing to maintain or replace it. As they’re only cheap parts, whilst they may last for many years they may also only last one or two. As they’re so cheap to buy I’m thinking of buying two so I always have a spare to hand as a quick swap if needed.
- I was also thinking that having the motorcycle relay close to the fuse box would allow me to have a back-up/fail-safe cable for a manual contact to the big 12V cable in the fuse box in the event of a failure and needing to pop the bonnet for a manual override if the motorcycle relay failed.
- how did you seal your relay? Did you manage to cover/ wrap it in something? I’ve seen a few on eBay UK which have a nice rubber cover which looks like a good solution like this one. If the rubber cover is a decent fit, a bit of silicone sealant and some cable ties would probably cinch up any potential gaps to keep the water out.

I have become obsessed with this starter upgrade and optimising my electrical system so really welcome your input and views on this!  Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

I used the main starter feed for the relay feed.
I fitted the relay at the starter solenoid so that the wire from the fuse box relay only needs to carry the small current to trigger the new relay, which was the only reason for fitting the extra relay. Having the relay down with the starter solenoid where it is exposed to mud and water isn't ideal but it has been quite clean the couple of times that I've checked it.

The cover in the linked advert would keep the terminals cleaner than mine which has no cover. I put some marine sealant around the join of the metal and plastic as I couldn't determine how good the internal seal, if any, might be. I suspect that sealing the unit itself would provide a more reliable seal than trying to seal a cover so probably best to seal the unit and add a dust/dirt cover without trying to seal it.

Graeme - legend! Thanks for coming back so quickly and really helpful too!

I completely understand the logic behind your relay location choice, in order to keep the original ‘trigger’ cable length minimised. Also good to hear that you’ve had no issues hooking up to the 12V +ve on the main motor feed. I’m admittedly new to all this but really do get into the details when researching and it seems that this is a really popular mod in Australia and the USA, but hasn’t really caught on here. However, when you understand the underlying logic and principles as to why the mod is done in the first place, it seems like a no brainier! It’s cheap and easy to do, and it’s an excellent preventative maintenance upgrade!

I’m thinking I will stick with my plan and locate the relay either in or next to the fuse box as I’m sure I’ll be able to find a place to tap-in to the original ‘trigger’ wire upstream of the starter motor. I might even see if I can find the source in the fuse box itself and tap-in there rather than cutting into the cable in the loom. Earth will also be a simple from that location. I can then make two brand-new high-spec cables to run from the big 12V +ve in the fuse box to the relay, and then another from the relay down to the starter solenoid. I’ll be sure to take photos and do a write-up!

My only other question for all is: what’s the highest current I’m likely to see passing from the 12V +ve feed through the relay and into the solenoid? Just thinking of cable choice and making sure it’s never going to be close to melting!! I’m thinking a 10mm2 welding cable with a 70A capacity is more than ample, but no point taking any chances and have the choice of 110A, 170A and even a 240A if necessary! Might seem like complete overkill but as it’s coming direct from a source linked to battery/alternator it’s not impossible to imagine a current surge at the point of startup whilst relay still connected! Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

If the resistance of the solenoid between the trigger terminal and earth is measured then the maximum current draw can be calculated but I suspect that it wouldn't be more than 15A but probably less than 10A. There won't be any surge from the alternator during cranking as the PCM waits several seconds to allow the engine to get up to speed before loading the alternator, as seen when the voltage is monitored.
Welding cable insulation is of poor quality compared with automotive power cable. I would never use it on a vehicle.
If running a wire from the engine bay then make sure that the supply end is appropriately fused to prevent the insulation burning if the insulation is breached, ie the fuse must blow before the insulation burns.

Had a question from a member about the new cable I fitted, so a few photos attached.
Cable run carries on behind headlight, then down to subframe & Starter.

Click image to enlarge

so Shaun, you went onto the backplane of the starter relay, or traced out the wire and joined into it there.... is that the black blob of insulation, on last pic? i can manage the cable run ok, if i just know where to interrupt the suspect wire itself.