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agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

GlowPlug physical access + please sense check my diagnostics

Hello all,

2.4 here with the P037D-29 (2F) error code: "glow plug relay sense circuit - general signal failure - signal is invalid"

... and a wee bit of white smoke on start that I'd like to clear up before the neighbors complain.

What I've done so far:

- Checked all fuses, all belling out continuity, some empty slots though.
- Checked the wiring, found 11Ω resistance in the wire between the harness lug and the glowplugs themselves, cleaned up the lug and stud. Now it's down to 1.4Ω.
- Checked for 12V at the lug with the key turned, got battery voltage at the lug for 16seconds. Indicating to me that the relay is operational and the plugs should be receiving enough voltage for enough time *.
- Disconnected the wire to glow plugs from the harness, (but not each glow plug from each other), and measured resistance. The lowest resistance I got was ~16kΩ which was on a plug that I filled/cleaned a small flat on to ensure a good connection with the DMM probe.

Unless I'm mistaken all this indicates that all four plugs have failed?

Either way, accessing them is the next step. Does anyone have any tips? They're buried behind a bunch of things that look like return fuel lines and air intake manifolds and so on. I could just open it all up and hope for the best but don't want to get dirt in things where it shouldn't, break gaskets that will need replacing, etc. Also, I don't know the torques for reassembly. Possibly I'm overthinking it and it's just common sense?

I've read the other threads, but they seem to have lost images that were uploaded. I'd be interested to know how the ECU is actually sensing the relay circuit, i.e. what values measured via what sense circuit are actually triggering that alarm.

Any help appreciated

(*Interestingly the voltage then went down to 6.5V after the 16s and stayed there until the key was removed, it then stayed at 6.5V for approx 10s after the key is removed) Solved the bowel problem, working on the consonants...

25th Oct 2021 10:27pm

dorsetsmith

Member Since: 30 Oct 2011
Location: South West
Posts: 4554

glow plug resistance each 0.7 ohm new prox

also with resistances in parallel total resistance is less than the smallest resistor

i.e. 4 0.7 resistances in parallel = 0.17 Ω

the only way to check them is one a time

what values measured via what sense circuit are actually triggering that alarm.

If ecu has call for glow plug and no 12v power feed back from the relay switch out put can seen at dash a DTC is logged for 2.4 only, as 2.2 glow plug system has its own ECU and power control

25th Oct 2021 10:55pm

agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

Thanks for the values, helpful!

I'd like to avoid the work of testing individually if I can otherwise use logic to prove it. That way I can just order the parts and disassemble once instead of twice.

The way I see it I have tested four in parallel (plugs disconnected from harness, resistance between cleaned random plug terminal and the actual battery ground lug). Now, given that I get very high resistance I assume all four have failed, as if one or more were working then they would provide a path that the DMM would see as some form of resistance at or below ~0.7Ω, and certainly not in the range of kΩ. Correct?

It'll be interesting checking them individually though, may plug 12V into them with a benchtop, see what happens, get a spare goody as well, try that too.

As for the access itself, from looking at past discussion it seems like there's nothing much to removing all the gubbins in the way. Or is everyone not mentioning that they had a WSM and a bunch of exotic tools and processes?

Solved the bowel problem, working on the consonants...

25th Oct 2021 11:11pm

agentmulder

Member Since: 16 Apr 2016
Location: Outer Space
Posts: 1324

dorsetsmith wrote:
If ecu has call for glow plug and no 12v power feed back from the relay switch out put can seen at dash a DTC is logged for 2.4 only, as 2.2 glow plug system has its own ECU and power control

I'm getting 12V on the wire to the plugs, can temporarily see the dash indicator for the plugs (as opposed to a fault light), and this fault code read via a BAS tool

Solved the bowel problem, working on the consonants...

26th Oct 2021 12:28am

dorsetsmith

Member Since: 30 Oct 2011
Location: South West
Posts: 4554

fuse 38 10amp (main fuse board) in line with feed back ctt

feed back go to ECU and ecu drives glow plug lamp in the dash

26th Oct 2021 10:46am

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