Good day

I have a 2000 Discovery II that is cranking strongly, but is not starting. M + S lights are flashing. Odometer is at 235000 km.

I have had this truck for just over a year now, and it was fairly problem free other than P1171/P1174 showing up recently. However, I did have a coolant leak incident last month, and a temperature gauge that began to creep above the middle of the gauge. It seemed to be coming from the back of the engine. Did a head gasket test with the test fluid, and that passed, so I decided to do valve covers/intake gaskets. With that done (some lower plenum bolts were finger tight), and some new plugs/wires, the truck was running fine. Finished that job last week. I've since put about 200km on it, and no leaks.

But those P1171/74 codes still kept showing up. I had a spare MAF that I had from a donor vehicle a whole back, and I swapped that in. Reset the logged codes and started it up. Started just fine. I was standing in front of the truck while it was idling, and just looking around the engine for any other possible sources of air leaks, and all of a sudden the truck shut off. About 5 minutes of idling. No odd noises.

I've swapped back to the original MAF, and no bueno. Disconnected the battery and reconnected it again after an hour or so, nothing. Strong crank, but no start.

Any ideas?

 

Check the rollover switch?

 

I've pressed it, seems fine? It clicks. Pressed it a few times but no luck.

 

Temp gauge doesn't slowly move on these - it sits in the middle until some ridiculously hot temperature, then swings up into the red in no time.

These things get super picky about voltages, especially the transmission computer. Try cranking it with a jumper pack hooked up as well - the starter may be pulling too much voltage if the battery is low, which'll mess with it. Could also be a coincidence that the XYZ switch when out at the same time.

 

The MAF isn't related to a no start condition. The truck will start and run with the MAF unplugged. If the truck was running and shut off suddenly it's not the inertia (rollover) switch either.

Sudden engine shutoff and subsequent no-start in a DII is very often caused by a failed crankshaft position sensor (CKPS).

V50-M66 is right about the transmission ECU being super picky about voltages. That's a very common cause of the flashing M+S lights. (Not sure why he mentioned the XYZ switch since it hadn't been brought up. According to the RAVE, a failed XYZ switch is only one of ~20 faults that can trigger the M+S lights.). The best way to diagnose the M+S lights is with a scan tool that can read the transmission ECU codes.)

And BTW, the P1171/P1174 codes indicate a vacuum leak affecting both cylinder banks. A smoke test can help identify a vac leak.

 

Thanks for the reply!

​​​​​​My cheapie code reader is showing pending codes of P1842/P1843. Checked all the fuses in under the hood and driver compartment. All good there. The battery is fairly new, and I did charge it just in case. I also have a shop charger/jump starter that I've tried.

Regarding the XYZ switch, I've never had issues with it, but I did inspect it, and it is caked on dirt and grime. I sprayed it with some contact cleaner. I should make a point to say that my disco has some rudimentary linkage installed for the CDL.

I think I will take a look at that CPS and report back.

 

You may call it a cheapie code reader, but if it can report P1842 and P1843 it's doing something right.

Do you have the RAVE? I includes tables for all sorts of fault codes. If not you can download a copy from the link in my signature and look them up.

• P1842 - * CAN level monitoring - Maintains current gear in low range, limp home mode in range. Shift pressure to maximum, harsh gear shifts/engagement.
• P1844 - * CAN time-out monitoring - Maintains current gear in low range, limp home mode in high range. Shift pressure to maximum, harsh gear shifts/engagement.

I am unfortunately not a transmission guy, so I can't help you with what any of that means or how to address it. But I would still check, clean, tighten and double-check the battery terminals. If that doesn't solve the M + S light problem I'd remove the center console and clean and check the connection for the trans ECU ground at connector C708 (found in the DII Electrical Library).

And again, none of this has anything to do with the truck not starting. Back to the CKPS for that, I think.

 

I used to throw the M+S for a period of time. I would always have to clean to connections and grounds. Retighten and it would go away....for a short time. I eventually had enough. Come out from a store and I was in limp mode M+S. I could never get the Positive terminal (stock) real snug. I ended up upgrading the "Big 3" with 1/0 cable and Mil-Spec terminals. Have not had an issue for over 12yrs with the M+S since then.

As for the P1174/P1171 issue I just dealt with this nightmare last June. I started w/ a new MAF I had on the shelf and several vacuum lines. Idle control valve. No Luck! In my case it was the fuel injector seal/o-rings. Several of my o-rings were hard/brittle. If you go that route you can send the injectors out and have them serviced. I used Mr Injector and recommend them. They send a full report back on the cleaning/flow rate before and after. They send new o-rings and your back in business. Good luck!

 

x2 on this.

had the same thing on my '04 for quite some time. ended up replacing the positive and ground battery cables and using Mil-Spec terminals. cleared up my M+S issues, as well.