Castle Combe 2024

[Steve A]

Dave is it worth disconnecting the LEDs and then retest it to see if the fault is still there if it is its not the LEDs.

I thought those LED's looked rather fetching Dave, I hope there not the cause of the problem, as I fancy a set

[muley]

Thank you to those who took part.

Special thanks to Dave P for organising the campsite ~ the folks there were so friendly and helpful ~ and the price was almost laughable.


Thanks to Steve and Lesley for sniffing out such a brilliant pub for the evening meal. Exceptional service there.

Having left a day earlier than originally planned I had an easy drive home and an extra day for gardening

[dapinky]

Dave is it worth disconnecting the LEDs and then retest it to see if the fault is still there if it is its not the LEDs.

It is certainly the LED Headlamp circuit that does it - I can drive on side/tail lamps for a long time with no CEL, but 2 minutes after putting the headlamps on, it illuminates. It is something on that switched circuit that it doesn't like - but I can't think what or why.

[Blaster]

Dave is it worth disconnecting the LEDs and then retest it to see if the fault is still there if it is its not the LEDs.

It is certainly the LED Headlamp circuit that does it - I can drive on side/tail lamps for a long time with no CEL, but 2 minutes after putting the headlamps on, it illuminates. It is something on that switched circuit that it doesn't like - but I can't think what or why.

I know some people have had a lot of radio interference from LED light driver circuits. The most obvious would be the lambda sensor. Try disconnecting the lights near it to see if the problem returns.

[dapinky]

Thanks Tony, I never considered RF interference, but it makes sense..... would shielding work?

[Blaster]

Thanks Tony, I never considered RF interference, but it makes sense..... would shielding work?

It may, but the problem maybe that the power lines to the headlight and the lambda sensor are running next to each other.

can you disable the closed loop and run the engine.

[dapinky]

I'd have to take the 1499 chip out of the ECU and unplug the O2 sensor - but it's do-able.

Firstly, I need to replicate it on the drive, so that any modifications can be assessed without needing to drive through rain!

[RonR]

3) The one which has me scratching my head is a bit off an oddity that I haven't heard of before, so I am hopeful that an electrical guru will know the answer..... as said, the weather was 'mixed' on the way home, and I haven't ever driven it in the dark...... so on occasion I had to put the headlights on. Then, after about 2 minutes of dipped beam use, the CEL came on but the gauges all looked fine and there was no noticeable change in driving conditions. When I turned off the lights, the CEL went out after 3 or 4 seconds. It did the same the next time I put the lights on.....
...... so, why? I don't know if it is because of the LED units I have fitted, or if it happened before with the OE lights as I never drove it under those conditions, so can offer no other information.

Just a shot in the dark here, but... Do you have a resistor fitted in parallel to the LED units? If so what resistance and wattage? Could be something to do with the resistor getting too hot after a short time and somehow affecting other circuits.

[Blaster]

When I went closed loop I did not realise that half the loom for the O2 sensor was missing. It would show itself as the engine lights coming on after about 2 minutes of driving.

[dapinky]

Ron,

That was one of my thoughts - I have probably "over-resistored" it - except it will be 'under' really with 2 in parallel (bloody electronics!!!!) with one each side. I can't remember what i ended up with now as they were swapped about - but it's another thing to look at, thanks.

Tony,

I was fortunate that all wiring was present on both of mine - luck of the draw (or age!).

[dapinky]

Right, an update!

My bad

I failed to read the codes correctly in my haste to see what the problem was and get home..... I miscounted the flashes, and instead of a series of "12's" there was (is?) a stored code "13" in the middle of them. No other stored code, though, so that helps.

I now realise that it is an O2 sensor (or wiring) issue which happens when the headlamps have been on for a few minutes. To me, this suggests an RF interference issue (as noted by Tony) or a 'hot resistor' issue as identified by Jonathan...

I have no time to look into it further until later in the week (except I will probably let life get in the way) - does the hive-mind agree with me that if it happens again, all that really happens is that the car reverts to 'open Loop' running at that time, so no harm is likely to occur?? If that is the case, then it is far less worrying than anything else going wrong, but I'd still like to clear it up. I have no plans to use the car at night or in rain that requires the headlights, so it will be an occasional occurrence anyway (the lights need only to work for the MOT).

This thought process would agree with my observation that there was no change in the actual driving ability of the car - the ECU is merely looking for a signal from the O2 sensor which is absent.

[chrism]

If it's any help I have a '90 SE that was extra-wired to run an O2 sensor and 1499 map.

When my O2 sensor de-pinned behind the driver w/arch there was no CEL and I assume that it was running a:f at 10.5:1 due to the mixture pot, but anyway the a:f wasn't the expected 14.7:1. Performance didn't change tho' it was a little more thirsty, smellier and MoT emissions were much higher. I didn't notice it for nearly a year until I tried the new EScan...(thanks fellas). EScan still read the ecu as 1499 but with the wrong a:f ratio

When I re-pinned it there was less smell, still 1499, an a:f ratio back to 14.7:1 and it was as economical again as Tuga's

I don't know if yours is an S2: If it is I'd expect the CEL to come on if the O2 sensor is denatured - esp since it doesn't have a fuel adjust pot (?) - but I can vouch for the fact that if it's a 1499/O2 sensored SE my CEL didn't light up when the O2 sensor failed.

[dapinky]

Thanks Chris,

It's an SE with the 1499 chip and O2 sensor. The sensor is fine (according to Elanscan when fitted) and all the wiring was already in the loom. The CEL only comes on (and logs the O2 sensor/circuit fault) when the headlights have been on for a couple of minutes, and it goes off again a few seconds after turning off the lights.

I will have to try and re-create the issue on the driveway and log it with ES whilst it does it to see exactly what the ECU is responding to - - and then try to work out what is actually causing whatever I find.

[chrism]

The sensor is fine (according to Elanscan when fitted)

...dapinky, does EScan read eprom 1499? - then so did mine when it wasn't connected...

Does it read a:f of 14.7:1? - then it should be working...

On flag 40 does it read 'closed loop''? - should be working...

Those are the only ways I know of that will confirm that the sensor is working - unless there's another way (such as multimeter-ing the unconnected sensor for 12V on one of the whites with engine ON ign light OFF/heater circuit continuity/the other white giving a good earth/~5ohms heater ciruit resistance

Code 13 deffo is the O2 sensor. My SE never threw a code 13 when it failed - which is why I suspect it defaulted to the mix pot when 1499 wasn't getting a sensor input, in my case. It did stay as 1499 tho' (I kept the EScan log)

I reckon if the sensor 'passes' you've gotta duplicate it whilst running EScan and somehow (by measuring the time interval?) identify these (above) parameters on EScan when it fails - to see if it's affecting the sensor values, which in turn is throwing the CEL.

Please keep us posted with whatever you do?

ps just a thought; does the red ign light come on when the CEL does? - cos that needs to be OFF to power the sensor heater...

[Tuga2112]

i dont understand where the RF interference idea came from. the O2 sensor signal is analogue, i would expect the alternator to generate far more RF interference than LEDs, but a simple test to that will be to use full beams, as that will drive more current throuhg the headlamps and should in theory make the CEL come out quicker.

Dave, is the green car running fine with the same set on closed loop ?

I Had a look at the wiring diagrams and cannot see a relationship between the circuits (alternator, headlamps. and my "top of the head" knowledge of close loop conversion).



on a separate note.
i didnt make it home as expected. my alternator stopped working. and the recovery truck had to get me out of the rain.
this morning i rushed throuhg the job i was halfway throuhg on my 4runner exaust manifold, and managed to put the M100 on the lift at 4pm. the intention was to take the alternator out, and replace with the one i advertised for sale...
but things didnt need to get that far, after taking the PAS reservoir out, remove the tension from the belt, and taking out the subframe... well the connector to the regulator was loose... so i plugged it back in. and made sure it was firmly installed, and put the belt and PAS reservoir back... start the car, and everything is fine.

[dapinky]

Chris,

Thanks for your thoughts, but it is overcomplicating things.....

.... yes, it reads 1499, yes the AF ratio was as expected for a closed loop system once it had warmed up and stabilised, no the ignition light didn't act odd.

It is purely (and only) playing up when turning on the headlamps (fine with side lights), and goes out a few seconds after turning off the lights. I am pretty sure that it is an issue with the LED driver circuit interfering with the O2 sensor, but until I get a chance to play cars it won't get looked at.

[Simon_P]

Check for a bad eart connection on the lights.

[RonR]

You beat me to it Simon!

And as the lights earth via the Longerons, also check the braids between the Longerons and the Main Chassis.