2002 defender cps issue

[mfc]

Hey all…stranded at home again.
Long story short ,I had a wire from the cps break and fixed it by twitching a scrap of wire in and taping it up……..ran perfectly for 3 months until I fixed it last night/today…….

Won’t start…had a cps fault from the plug….also a no tach drive [there’s none on the car]
I’ve a spare cps and I’ve tried that as well…both have the same ohm reading …

I’ve tried purging the fuel rail

Checked all fuses n relays

Cleaned ecu[was clean already] plugs and engine plug

As far as I see there’s 2 other options

Cut back the cps Leads a bit and solder on a new section,check fuel presure reg wires to as they came off….

It’s a battery/alternator issue…….I had a dead flat[clicking relay flat] and I’m fairly certain I’d left nothing on[98%]….it’s on charge but at 12.7 of the charger…no go..drops to 12.3 after 10 sec’s key
My alternator is low ish on output as well[I’ve a spare]13.2 to 26v …
Battery colapsed?

All sugestions greatly appreciated as it’s 30 km to town
Cheers mark

[Tins]

Dunno about Deefers, but my TD5 disco won’t start if the battery is even a little low.
As for the CPS wiring, mine has had it cobbled together for about 18 months now. Never seems to be a problem.

[p38arover]

CPS?

Cycles per second - aka Hz?

[one_iota]

CPS?

Cycles per second - aka Hz?

It's a TLA

[shack]

CPS?

Cycles per second - aka Hz?Crankshaft position sensor.

But I'm guessing you already knew that!

[mfc]

Dunno about Deefers, but my TD5 disco won’t start if the battery is even a little low.
As for the CPS wiring, mine has had it cobbled together for about 18 months now. Never seems to be a problem.

Yea I’m thinking it’s colapsed……I had it on full charge and the voltage on the nanocom dropped from 12.8 to 10.3 in 5 cranks
I’m thinking the ecu needs 11+[11.9 v?]….starter might have been a bit slow.

Batterys off the car to see how it behaves [overnight 4c here] see what the v drops to
Cheers

[discorevy]

Yes, check the battery for spikes.... I think it's Cactus

[p38arover]

Crankshaft position sensor.

But I'm guessing you already knew that!

No, I didn't.

[akelly]

I had a world of trouble with the CPS wiring on mine after I put in the new engine. Ended up raiding an unused plug that was hiding up beside the brake booster and soldered it in, has been fine since then. I found advice online saying not to solder to the loom but the available space is so short there was really no choice. I keep meaning to go back and shield that section but haven't yet.

If you're getting CPS faults and you know the sensor itself is good (mine was new) then the loom is probably the issue - it's a bad design.

[mfc]

I had a world of trouble with the CPS wiring on mine after I put in the new engine. Ended up raiding an unused plug that was hiding up beside the brake booster and soldered it in, has been fine since then. I found advice online saying not to solder to the loom but the available space is so short there was really no choice. I keep meaning to go back and shield that section but haven't yet.

If you're getting CPS faults and you know the sensor itself is good (mine was new) then the loom is probably the issue - it's a bad design.

Yea there both good[cps] but the plugs crap……..was searching for one to scrounge

I’m betting on dead cells in battery as well ….won’t hold over 10ish volts on nanocom whilst cranking

[Tins]

Yea there both good[cps] but the plugs crap……..was searching for one to scrounge

I’m betting on dead cells in battery as well ….won’t hold over 10ish volts on nanocom whilst cranking

I fitted my trans on my back in what was essentially a paddock. Doing this I got the CPS caught up in the bellhousing. No way was I taking it out again, so the car has a Jag CPS soldered into the old loom, as there's no other way on a D2 other than rewiring and repinning it at the ECU, or replacing the whole engine harness. Runs fine.

Of course, I'm "gunna" fit a decent plug......

EDIT: I don't think the CPS wound up in with the flywheel, but the plug sure did.

[akelly]

Yea there both good[cps] but the plugs crap……..was searching for one to scrounge

I’m betting on dead cells in battery as well ….won’t hold over 10ish volts on nanocom whilst cranking

Yeah if you're not getting over 11v cranking on the nanocom you're in strife. Probably a combination of a few things, as usual with the bloody TD5... [bigwhistle]

[mfc]

Yeah if you're not getting over 11v cranking on the nanocom you're in strife. Probably a combination of a few things, as usual with the bloody TD5... [bigwhistle]

I’m thinking that I’ve got a break in the cps wire below my repair or possibly the fuel temp wires, although both these should leave a code..

Will a buggered alternator stop a td5……I’d think that the voltage drop on a new battery whilst cranking could be a buggered alt[got a spare somwhere] ?

I’ve even bypassed the fuel cut of switch

[mfc]

Good voltage in under seat box and relays checked ……all fuses good..
Headlights [leds ]flashing[ rather than flickering] and dimming slightly on cranking……
I’ll check the connectors on starter and alt when it’s dark[easier in confined spaces]

I’m realy thinking the alts **** its self, killed the battery as I tried to start it on the old battery…
Don’t fancy trimming the loom back for no reason..,the wire is like glass…I’ll cut another cm of the tubing back to make Shure I haven’t melted insulation and it’s shorted.

Opinions or options greatly appreciated
….everything except cranking voltage checks out
Regards mark

[akelly]

one thing to check is that the CPS wires aren't anywhere near the starter - they need to be kept back as far as you can have them from there. Your nanocom would be showing other faults like alternator I think? Having been through this I feel your pain, I was at it on and off for about 2 months trying to get my new TD5 to start. Ended up being about 5 different things and I chased them round and round.

In the end the TD5 is a very simple engine, there's only two things that will really stop it - fuel pressure and the f-ing crank sensor.

[mfc]

one thing to check is that the CPS wires aren't anywhere near the starter - they need to be kept back as far as you can have them from there. Your nanocom would be showing other faults like alternator I think? Having been through this I feel your pain, I was at it on and off for about 2 months trying to get my new TD5 to start. Ended up being about 5 different things and I chased them round and round.

In the end the TD5 is a very simple engine, there's only two things that will really stop it - fuel pressure and the f-ing crank sensor.

I can’t see any alternator on the nanocom…only voltage dropping on cranking,everything checks out …I’ll jumper lead from battery to starter and try that …only thing I haven’t checked yet is that there’s not a short between the 2 cps wires at an older repair….though I’d have thought Ud get a cps or taco code on the nanocom

Otherwise alternator out tomorrow

[akelly]

the CPS error codes are notorious for not showing up. I think (but not 100% sure) that if your alternator was giving trouble you'd get a fault code in the nanocom.

The whole time my CPS wiring was playing up I never got a fault code, the only time I saw one was when I disconnected the CPS and cranked the engine.

Are you getting RPM showing up on the board instruments page when you're cranking it over? RPM needs to be over about 300 (from memory) for the CPU to allow a start.

[mfc]

the CPS error codes are notorious for not showing up. I think (but not 100% sure) that if your alternator was giving trouble you'd get a fault code in the nanocom.

The whole time my CPS wiring was playing up I never got a fault code, the only time I saw one was when I disconnected the CPS and cranked the engine.

Are you getting RPM showing up on the board instruments page when you're cranking it over? RPM needs to be over about 300 (from memory) for the CPU to allow a start.

I had them up until I’d trued to start it……..cleared them…..then purge fuel rail so no more codes
The rpm is somthing to check…I think I’m not even getting an rpm reading

[akelly]

no RPM on the board instruments page = no CPS signal.

[Tins]

A buggered alternator will stop a TD5, but I don’t know if it will prevent it from starting with a full battery. Probably not.

The CPS should at least illuminate the MIL if faulty or if the wiring is defective.

[Tins]

BTW, are we assuming that the starter is good?

[mfc]

Yes, at the moment……I’ll check at first try this morning to check if the rpm,s hit the required level…..with jumpers from bat to starter ..I’m asuming that all tachometer /speed etc comes from the cps

[Tins]

OK, I am far from being a guru on this, there are folks here that are.

That said, I have some experience with this issue. In your first post you mentioned checking two CP sensors with a DMM, with similar ohms. Do you remember what the readings were? IIRC they should be upwards of 200Ω, but not zero or OL.
When you repaired the "twitch" did you remove the CPS from its location?
When you turn the key to "ON" does the MIL perform its self test and then go out? Does it come back on when you try and start?
My memory of this is that the MIL will illuminate if there is any fault with the CPS other than the air gap, which is why I ask if you removed it. They are reasonably sensitive to excessive air gap.
I can see why you suspect the CPS, given your problems seem to start when you ****ed with it, but it could be coincidence, or it could be you disturbed something else while you were at it. As mentioned, TD5s are simple beasts, but they are quite sensitive to low voltage, and that's where I'd be looking now. The voltages you mention seem totally inadequate. I take it you have no other vehicle or jump pack to try a jump? When you were near the CPS is it possible you disturbed the wires to the starter? A loose batt terminal there could cause sufficient voltage drop to create issues.
Not a very coherent post from me, I'm just throwing ideas.

[mfc]

OK, I am far from being a guru on this, there are folks here that are.

That said, I have some experience with this issue. In your first post you mentioned checking two CP sensors with a DMM, with similar ohms. Do you remember what the readings were? IIRC they should be upwards of 200Ω, but not zero or OL.
When you repaired the "twitch" did you remove the CPS from its location?
When you turn the key to "ON" does the MIL perform its self test and then go out? Does it come back on when you try and start?
My memory of this is that the MIL will illuminate if there is any fault with the CPS other than the air gap, which is why I ask if you removed it. They are reasonably sensitive to excessive air gap.
I can see why you suspect the CPS, given your problems seem to start when you ****ed with it, but it could be coincidence, or it could be you disturbed something else while you were at it. As mentioned, TD5s are simple beasts, but they are quite sensitive to low voltage, and that's where I'd be looking now. The voltages you mention seem totally inadequate. I take it you have no other vehicle or jump pack to try a jump? When you were near the CPS is it possible you disturbed the wires to the starter? A loose batt terminal there could cause sufficient voltage drop to create issues.
Not a very coherent post from me, I'm just throwing ideas.

Started first up thismorning…..I used jumpers between bat and starter [3c outside] 3 turns…
Now I cut back that epoxy shrink wrap and there was contact between a strand of cpu wire and the shielding …and posibly picked up and soldered in by me…cleaned that up.

Alts putting out 14.7 at idle and at about 2400 rpm…..voltage on nano dosent drop on cranking
..guess now’s time to check the alt in car under load and posibly the starter..
Just to make Shure ..
Thanks everyone , there contancerous things…a few little things and they run like **** lol…fix them and there a different car
Cheers mark and god bless mr nanocom lol

[Tins]

Good news. Problem is that when you fix two things you don’t know which one solves the issue. I would be getting that battery checked, but perhaps the possible short in the CPS wiring was the problem and prolonged cranking was draining the battery 🪫
With a full battery a TD5 should start almost instantly. Glad you got it going, and thanks for the update. I wish more people would come back and report how a problem was resolved.