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Zed

Member Since: 07 Oct 2017
Location: In the woods
Posts: 3278

2010 Defender 110 Puma 2.4 XS CSW Santorini Black

Help please, I have a haunted accelerator pedal!

A while back I thought I had a an overboost issue or perhaps sticky turbo but it only happened once and then disappeared so I thought nothing more of it, mainly because I had a broken transfer box and other stuff to deal with.
Last week however I started ignition and the car started normally but the battery was light on, it was also showing zero volts on my OBD gauge. It hadn’t struggled to crank so I ignored it and after a few seconds the light went off and gauge showed normal voltage. However idle revs were at 900 instead of 800 and throttle had a bit of lag and revs were hanging. As I rolled off the throttle the revs didn’t drop off as they should. Slightly concerning but I carried on, as by now I was on a dual carriageway with nowhere to stop safely. Then much more pronounced lag and at one point I literally had pedal to floor trying to keep up with traffic but no acceleration at all, then seconds later full acceleration with no pedal input at all. Very twitchy bum time for a moment! I managed to find a safe place to pull over, turned off ignition, waited a minute and restarted. No battery light, revs back to 800 at idle and seemed to drive normally, although I couldn’t really test as there was too much traffic.
Since then the battery light has come on twice at start up. Both times I turned off, turned the key and it was back to normal. I really don’t fancy recreating the experience.
Has anybody had similar issues? My guess is something electrical causing it. I removed the OBD gauge (battery light issue happened since), checked the fuses in box under steering wheel plus checked a couple of places I know the loom can rub in engine bay but all looked ok, to the naked eye at least. I have ordered a new clutch switch but I don’t think it’s that.
Bar an exorcism does anyone have any suggestions to solve or what is causing the problem? WARNING.
This post may contain sarcasm.

2nd Jun 2024 9:52am

jim4244

Member Since: 13 Apr 2014
Location: Bedfordshire
Posts: 775

2007 Defender 90 Puma 2.4 CSW Zermatt Silver

Hi Zed

I'll just put this out as a possibility, but could it be that your battery is on its way out and your VCV is also on its last legs???

I'm sure that folk will be along with other possibilities..

Jim

2nd Jun 2024 11:25am

Zed

Member Since: 07 Oct 2017
Location: In the woods
Posts: 3278

Thanks for the reply Jim. VCV was changed 8 months ago, a Denso from Pete Bell. It could be a problem but the symptoms are very different from when the last one died.
Battery is a good shout as it’s a few years old but I haven’t had any issues with it and voltage seems ok. The alternator did cross my mind though. WARNING.
This post may contain sarcasm.

2nd Jun 2024 11:51am

Ianh

Member Since: 17 Sep 2018
Location: Essex
Posts: 1997

Perhaps an Intermittent earth issue, one that serves the throttle pedal ? There is a common Earth point on the bulkhead in the engine bay that’s worth checking, cleaning contacts etc.

2nd Jun 2024 12:16pm

Zed

Member Since: 07 Oct 2017
Location: In the woods
Posts: 3278

Thanks Ian. That’s exactly the type of thing I was thinking of, loose connection, wire rubbed through etc. Whereabouts is that earth point? WARNING.
This post may contain sarcasm.

2nd Jun 2024 12:22pm

Ianh

Member Since: 17 Sep 2018
Location: Essex
Posts: 1997

This topic provides good info on the earth locations in engine bay, behind dash etc with pictures. https://www.defender2.net/forum/topic48404.html

Worth checking the wiring diagrams to see which earth point could potentially be the culprit.

Ps, when the battery light comes up on the dash, are all the other dash gages still working ok ? If not it could be ignition switch or battery terminal clamps need loosening, tapping down and re tightening.

2nd Jun 2024 12:58pm

Zed

Member Since: 07 Oct 2017
Location: In the woods
Posts: 3278

Thanks that’s very helpful, exactly what I need.
Yes it was only the battery light. All the others went out as usual with just the battery light showing for about 30 seconds, maybe a minute while voltage showed zero on gauge. Then it went off and gauge showed normal. WARNING.
This post may contain sarcasm.

2nd Jun 2024 1:23pm

Ianh

Member Since: 17 Sep 2018
Location: Essex
Posts: 1997

If it was not for the battery light staying on for a while on the IPAC I would think it’s the throttle pedal sensor(s), the wiring to the throttle pedal, or the connector.

Have you read any DTC’s ?

Worth removing the connector to see any moisture or corrosion and giving it a clean. Check the loom, especially where it goes through the bulkhead, and test the throttle pedal sensors. There are a few topics on here re fault finding on the throttle pedal.

2nd Jun 2024 8:23pm

Zed

Member Since: 07 Oct 2017
Location: In the woods
Posts: 3278

Thanks. No codes thrown up, because that would be too easy!
I’ll have a search on here to see how to test throttle and sensors. WARNING.
This post may contain sarcasm.

2nd Jun 2024 9:13pm

Zed

Member Since: 07 Oct 2017
Location: In the woods
Posts: 3278

Right, I’ve checked all the earth points I can find plus every part of the loom that I think may rub and all seems well. I’m thinking it may be an idea to change the alternato. It’s the original part and one of the only things not replaced under my bonnet!
Does anybody have a recommendation or know the original manufacturer? WARNING.
This post may contain sarcasm.

6th Jun 2024 2:53pm

Ianh

Member Since: 17 Sep 2018
Location: Essex
Posts: 1997

I spotted this in an old topic. So it does seem the battery light staying on during initial start, and potentially the throttle issue , is an intermittent charging issue.

Lorryman100 wrote:
The battery light on the IPAC is part of a simple circuit that looks at the voltage that the alternator is producing, and if that voltage is to low it turns on the battery light on the IPAC. The battery light indicates a battery charging issue and not the charge state of the vehicle battery. If the battery light was on all the time the vehicle battery would lose its charge through use, as it is not getting a top up charge from the alternator

HTH.

Have you tested the voltage across the battery (with a multimeter ) when you initially start and the red battery light is on ? It should be circa 14 volts. If circa 12 volts or less that will indicate a charging issue.
If a charging issue then checking cable and connections from the alternator would be next, and if they are ok then that leaves the alternator.

Re the alternator, I think a genuine new Bosch one seems to be the cheapest quality replacement.

A useful read https://www.defender2.net/forum/topic48237...alternator

Especially Blackwolf’s post.

blackwolf wrote:
It's worth checking that the harness from the alternator to the back of the engine is all ok, it is a very coomon occurrence on the Puma for if to chafe anywhere it touches the engine causing broken wires, shorts, and potentially spontaneous combustion.

The only way to do this is to cut most of the cable ties and visually inspect the harness bundle. ALL the engine wiring runs in this harness and damage can cause a whole multitude of seemingly non-related faults.

A Tdci alternator should be good for 250k+ miles.

6th Jun 2024 4:21pm

Zed

Member Since: 07 Oct 2017
Location: In the woods
Posts: 3278

Thanks Ian, that will be next on my to do list. These intermittent issues are so frustrating but I’ll get there in the end! WARNING.
This post may contain sarcasm.

6th Jun 2024 4:38pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20339

Failed clutch switch or on its way out, or OBD device interfering with the ECM.
Which motor shindig be seeing at least 13.8v minimum. 14.1 to 14.8v is the sweet spot of a good current producing alternator and the voltage should be relatively stable at idle without loads going on or off.

Power surges are normally I found clutch switch related, limo mode turbo actuator sticky.
All sorts of things can happen if main primary power is loose or disturbed such as a loose ground, or battery clamp.
Might be worth noting all DTC’s and clearing them, disconnect battery after for 15 mins then reconnect after.
Usually these things are intermittent but not really serious or that costly, most of the time anyway.
The VCV causes poor performance, low mpg but more notably lack of top end power especially in 6th.
A little rough idle worse in cold weather but when it’s in its death throes will just cut out the engine, and then get just worse and do that more often just cuts out the engine.

Defiantly try disconnecting ECM related OBD devices though, they can cause problems.
If you’ve had to pedal to the floor, that’s limp mode, when I’ve had that once before it wad the turbo actuator stuck open that reset by itself once home, but after lubing the pivots it never came back and the DTC told me it was turbo actuator related.

Just suggestions at least, good luck.

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Last edited by custom90 on 6th Jun 2024 7:18pm. Edited 1 time in total

6th Jun 2024 4:38pm

Zed

Member Since: 07 Oct 2017
Location: In the woods
Posts: 3278

Cheers Steve, I’ll definitely try disconnecting the battery. My initial thought was also the OBD gauge as they are infamous for causing trouble, also a piggy backed fuse I was running an extra USB on, but the issue returned anyway. VCV is good but a new clutch switch I ordered arrived today so that will be next on the list along with checking alternator connections. Next week I’m finally dealing with my leaky slave cylinder so I will be able to check all those hard to reach electrical points while fitting a new clutch and assorted gubbins. WARNING.
This post may contain sarcasm.

6th Jun 2024 7:16pm

Martin
Site Admin

Member Since: 02 Apr 2007
Location: Hook Norton
Posts: 6605

2015 Defender 90 Puma 2.2 XS CSW Montalcino Red

Battery light on cluster is controlled over CAN from the ECU.

The ECU monitors the alternator charging status.

1988 90 Td5 NAS soft top

2015 D90 XS SW

6th Jun 2024 8:09pm

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