Not Your Average "Won't Start" Issue
 

I have scoured every Land Rover forum, blog, and YouTube channel about this issue, but alas I've resorted to switch from "long time listener" to first time "caller" by creating an account and reaching out to my fellow enthusiasts. I bought my '04 Disco II back in November of 2023. She has a laundry list of issues but the interior is mint, mechanicals in generally good shape, and I wanted a project car so I promptly ordered ~$4k in parts to start fixing her up myself. My father was a diesel & auto mechanic for 35 years until he suffered a heart attack and passed away on the job or I'd be on the phone with him trying to diagnose this. I owe all my engineering prowess to him and am not shy around vehicles so I've been happy to dive into fixing up the Disco II.

TLDR; here is the sequence of events:

1. Starting around May 2024 she started suffering from intermittent starts. Turn the key, click, turn the key, click. If I let her sit for a few minutes, hours, days, eventually I would go to start her again and she'd fire right up like nothing mattered. After searching the forums I learned it is common for the orgiinal starter to go, so I ordered a new one and started reading & prepping more for the tedious removal and installation
2. At the end of July I finally found a free weekend to get under the hood. Prep payed off and I managed to remove the old and reinstall the new starter in a few hours. A few test starts, all successful, were followed by a few short range test drives/parks/engine off/starts around the block in case I needed to push her back to the garage. Again all successful.
3. After a few days I decided to give her a real test. The missus and I took her on about a 40 minute drive to get lunch. We parked, I tested the starter one more time in case I needed to make arrangements while we ate, but she fired right back up, I let her idle a bit, and then turned her off.
4. As we were leaving lunch, catastrophe struck. The Disco started fine, we pulled out of the parking lot, and merged onto the highway. Cruising at about 60mph I get the flashing M&S and we go into limp mode. Familiar with M&S, I pull into the closes gas station, turn off the engine, go to restart thinking it should clear itself, but no start. No attempt to turn over, not even a click from the relay. I push her into a parking spot out of the way, ordered the missus an Uber and called a tow truck. $200 later and the Disco is back home, unable to move.
5. After more research I discover that the XYZ Switch could cause the engine not to start, and my code reader confirmed that with a P0705 Transmission Range Sensor Circuit Malfunction (PRNDL INPUT). I cleared the code and could see the dash reflect the gear selector which was also properly illuminating, but she still wouldn't start.
6. Back under the Disco! My prep paid off once again and I was able to get the switch out in about 30min, took it apart, cleaned all the components with CRC Electric Cleaner, packed it lightly with petroleum jelly, and closed it up with a set of nuts & bolts, and thew it back on the trans. The dash still matched the gear selector and the code was cleared, but the Disco still wouldn't start, but now the relay was clicking again.

And now I'm at a complete loss. I did the BCU/ECU "reset" trick by disconnecting the battery and touching the pos and neg leads together for a few minutes, reconnected the battery and tried starting. No luck. I'm not sure what else to do that this point. New starter, good relay (even tried swapping it with the headlamp powerwash relay), XYZ Switch functioning properly, could I be missing something else somewhere?

Any help is much appreciated.

Have you tested your battery or tried jumping from another vehicle or jumpack?

Are you getting 12v at the starter?

Have you tried changing the crankshaft position sensor aka the CKPS?

Is the engine trying to turn over or does it just light up the dash and no sound when you turn to start? Immobilizer?

Basic troubleshooting - it helps to understand the basic starter circuit and the components. Suggest looking at the Rave wiring diagram.

https://extinctmotorsports.com/d2-rave-page/

You can remove the starter relay in the fuse box and jumper the terminals 87 to 30 simulate a properly functioning relay.

• Works - look upstream
• Does not work - Does solenoid starter click? Potential loose cable. Jumper batt cable on starter using screwdriver from below. The two big nuts on the back of the solenoid.

If the issue is upstream, test terminal 86 for voltage and 85 for ground with the key in start position. If no voltage, check fuse 23 in inside fusebox. If no ground - security or bcu issue.

• Works -

I have experienced similar issues you described in number 1 then followed by M+S. As mentioned check your battery. Make sure the connections are snug/clean. An issue that can happen is bad battery terminals/connections. In my case, I could tighten the OEM battery terminals but it wasn't enough. They just didn't snug up and work well with the Optima Red Top I had at the time. The Fix: Upgrade the Big 3. I went with 1/0 cable. Change out the OEM terminals to Mil-Spec or whatever. Definitely check your ground connection/wire at the shock tower or chassis. Make sure it's not corroded. M+S/Limp Mode and poor battery connections are responsible for what you have described.

Good advice, I recently had an issue with one of mine being corroded under the ground cable connected to the alternator bracket. Unexpected!

@gecko951

• The battery is new from November (I know, new batteries can have issues too), so I did try jumping it with my other car this afternoon to no avail
• CKPS is a possibility, I'll return to that option as a last resort after looking into the suggestions from Extinct and Windycity_rover. $50 OE from Bosch on Amazon isn't a bad investment

@Discoidiot, dash lights up normally and all lights extinguish as expected, relay clicks when the key is turned. No immobilizer present on this vehicle

@Extinct, I'll jimmy a jumper for the relay and test first thing in the morning when the parts store opens. Fortunately there's one just a block away, so when they open at 9AM I can also grab the upgraded cable & connections at Windycity_rover's suggestion. I will mention that the battery terminals and terminal connections from the cable are all very clean and tighten down well, but I'll have them on standby regardless in the event jumping the relay doesn't work, indicating a loose cable or corroded ground.

@joefred16 For clarification's sake does the Disco turn over or do you just get a click, the troubleshooting path is very different for each of those. It sounds like the disco does not turn over, based on your the turn the key click.

Try this:

1. Engine cold overnight check you battery voltage 12.5 to 12.7 is pretty normal
2. While you watch the multimeter have someone try to run the disco over, you will get a big voltage drop but should stay above 10 volts
3. Now this is the tough part get the alternator checked if you can not get it started,

If you can get it started check the voltage output from the alternator as follows

• Positive at the alternator to the alternator body 14.2 to 13.8 volts
• Positive at the alternator to the ground on the block just below the oil filler 14.2 to 13.8 volts
• Positive at alternator to the battery negative 14.2 to 13.8 volts

It is very possible your alternator is failing, and you are getting just enough to kind of charge the battery. The dash warning light should come on but I am not sure of the conditions for that.
My Disco has started at 10 volts indicated, voltage when my alternator went, but it kills the battery.

Hi Richard, to clear things up I am getting a click on key turn, no crank. Thanks for the tip, I'll check the voltage in the morning as well. A multimeter is missing from my arsenal of tools so I'll pick one up at the parts store in the AM as well.

A quick internet search shows alternators aren't too bad price-wise, maybe $200 if I'm lucky. So worst case I can order one once I've done a diagnosis.

I don't understand this statement. All DIIs have immobilizer circuitry.