Member Since: 23 Dec 2009
Location: Cambs
Posts: 14
Engine Faults and cruise control problem with headlights on
Hi Folks,
2005 TDV6.
Had a strange set of faults on a drive the day before yesterday.
1st cruise control dropped out and wouldn't stay engaged. No fault warnings but the light would come on and almost immediately go out again, though it would try and maintain a set speed for those brief seconds it was on.
Then I started getting a drop in power with an engine system fault warning but this would clear as soon as I changed my position on the throttle pedal (increase or decrease).
Finally it stopped shifting automatically through the gears, though command shift would work.
When safe to pull over, stop and restart this seemed to fix the gears issue but the cruise problem and engine fault remained.
I read the codes on IID the yesterday but there were no engine faults or anything else that seemed to be linked stored.
The truck drove faultlessly during the day, but the fault recurred in the early evening, and I was able to establish that it was linked to the headlights being on.
Any ideas if there is a common cause for these? I wouldn't have expected a voltage issue from the battery with the engine running, as the Alternator seems to be charging strongly. Could it be an earthing issue somewhere?
Many thanks
MW
17th Jun 2020 11:01 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10374
could be an earthing issue on the rear brake light bulb holders.
could be poor quality brake light bulbs
or even the brake pedal switch
also check no water down the sides of the interior / under carpet
Member Since: 23 Dec 2009
Location: Cambs
Posts: 14
Thanks Both,
I'll start by looking at those areas. We have had a couple of showers after the long dry spell so water ingress could be responsible.
Could a brake light / switch problem be responsible for throwing up the momentary engine faults? Is the car clever enough to refuse to accelerate against the brakes?
Had loads of electrical issues when I first got my D3. First thing I did was replace the brake switch as it was a cheap and easy test. All the faults disappeared once changed. At least they disappeared until the next set of issues
I think that quite a few of us have a brake light switch to hand ready to fit - I certainly do.
NJSSAm I Gammon or Woke ? - I neither know nor care.
2016 Discovery 4 Landmark
2011 Mercedes Benz SL350 (R230)
1973 MG B GT V8 - 3.9L John Eales engine, 5 speed R380 gearbox, since 1975.
1959 MGA roadster - 1.9L Peter Burgess Engine - 5 speed gearbox
Past LRs - Multiple FFRs, Discos & a Series I - some petrol, some diesel,
none Electric or H2 fuel cell - yet.
There are 10 types of people in this world: Those who understand binary, and those who don’t.
17th Jun 2020 1:14 pm
Mike Whiskey
Member Since: 23 Dec 2009
Location: Cambs
Posts: 14
I think I'll do the brake light switch regardless then, since it looks like an easy job.
Otherwise i'll stick to daylight running only
17th Jun 2020 1:16 pm
Mike Whiskey
Member Since: 23 Dec 2009
Location: Cambs
Posts: 14
So I found that my sunroof drain was leaking on the drivers side, but there was not any water in the wiring 'channel'. Fortunately my carpet was still soaking it up.
Anyway I've repaired the sunroof drain and changed the brake switch. Just waiting for the carpet to dry out and I can go for a test drive. I'd just pull the carpet out but it appears they install it first, then build the entire interior on top of it....
So I've done one necessary job, which may or maynot hve fixed the problem, and am now waiting for the interior to dry on the wettest day of the year.
From bitter experience on my old D3 they take an age to dry out. I mopped up all I could with towels, and then ran a dehumidifier in the car for, IIRC, more than 2 days before it dried out.
NJSSAm I Gammon or Woke ? - I neither know nor care.
2016 Discovery 4 Landmark
2011 Mercedes Benz SL350 (R230)
1973 MG B GT V8 - 3.9L John Eales engine, 5 speed R380 gearbox, since 1975.
1959 MGA roadster - 1.9L Peter Burgess Engine - 5 speed gearbox
Past LRs - Multiple FFRs, Discos & a Series I - some petrol, some diesel,
none Electric or H2 fuel cell - yet.
There are 10 types of people in this world: Those who understand binary, and those who don’t.
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