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#1612549 - 03/12/2017 19:48 Widget displaying 2 faults
Edinburgh Offline
Club member 225
Je suis un Coupé

Registered: 04/03/2007
Posts: 9957
Loc: Auld Reekie
This has been a useful piece of kit I purchased from Theresa around a year ago!

So on the way back from Carlisle with the lads this morning we suddenly lost power, exactly the same way that first happened in April on the way to Assen then again in early May. Coasted along a bit off on to the M6 slip road and just at the bottom the engine caught again as I'd hoped. Looked at the widget which said the same as the occasions before
click to enlarge




Later, sitting in heavy traffic in Edinburgh the temperature went up higher than I expected and I couldn't hear either fan coming on.
click to enlarge

I turned the heater full on + blower and perhaps by chance the temperature began to drop - and fast, reaching 93C from 103C in seconds - as if the fan had activated but I couldn't hear it, even with the bonnet open.

What was strange when I opened the bonnet was the lack of a big wave of heat coming from the block, quite unlike lifting it after a track session when it hits you in the face.

Is this indeed likely to be connected to the widget's warning of temp sensor failure?

Also is there any connection with the crank sensor failure? A new one was put in only in May...

Or perhaps a dodgy ground/earth nearby which is causing wrong signals to the widget?



Edited by Edinburgh (03/12/2017 20:41)
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#1612559 - 04/12/2017 13:01 Re: Widget displaying 2 faults [Re: Edinburgh]
GrahamL Offline
I need some sleep

Registered: 17/12/2005
Posts: 3471
Loc: Pothole City
A crank sensor fault can cause the engine to cut out so that makes sense and is probably genuine. Could be bad connection at the plug or wiring problem or maybe the new sensor is dodgy, it can happen.

Does the widget always automatically show any stored errors, or only if the injection warning light is on?

I had crank sensor errors appearing occasionally (with no warning light) but the engine never cut out or failed to start. Replaced sensor and it's been fine since with no errors, so the ECU can flag a minor or intermittent problem with the crank sensor which would never be noticed if you weren't actively scanning for codes.

The range for the water temp sensor is -35 to 130 degrees, so given that you didn't appear to be showing close to those values the error will be due to "signal not plausible (different from that estimated on the basis of engine conditions)" rather then being completely out of range. It doesn't say what those engine conditions are.

Once the water temp error is detected the ECU will switch to using the intake air temp for the water temp for 3 mins if the air temp is less than 20 degrees, otherwise (and after 3 mins in any case) it'll assume water temp is 80 degrees. Also the radiator fans should activate on high speed 8 secs after water temp error detected. It doesn't say for how long.

Would be interesting to see what the ECU thought the intake air temp was when the water temp error was flagged.

Have you cleared the error codes now and is it all OK after a re-start?


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#1612584 - 04/12/2017 18:29 Re: Widget displaying 2 faults [Re: Edinburgh]
dante giacosa Offline
Club member 1447
My life on the forum

Registered: 25/05/2012
Posts: 1787
Loc: Going North on the A9
Hey Graham-

are the engine fans brought in from relays controlled by the ECU..?

Would I be right to say; one is on the fusebox, and the other on the NS suspension turret..?

Would a loss of ground connection to the coolant temperature sender cause the ECU to see it as 'out of range'..?

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#1612587 - 04/12/2017 18:48 Re: Widget displaying 2 faults [Re: Edinburgh]
barnacle Offline
Club Member 18 - Membership Secretary
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Registered: 17/12/2005
Posts: 31764
Loc: Hemel in the Hempstead
The widget shows current errors; i.e. only those currently active. It doesn't delete errors from the ecu though, so if you ask it through the terminal you'll get everything that's stored.
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#1612591 - 04/12/2017 19:36 Re: Widget displaying 2 faults [Re: Edinburgh]
GrahamL Offline
I need some sleep

Registered: 17/12/2005
Posts: 3471
Loc: Pothole City
The coolant temp sensor doesn't have a ground. The sensor is just a thermistor and the ECU detects the voltage drop as it gets hotter.

One pin is power from the ECU and the other pin is the signal return. If it shorts to ground the temp reads over 130 degrees and flags an error, if it shorts to +12v or goes open circuit it reads under -35 degrees and flags an error.

If it's an aircon car the high speed fan relay is in the control box on top of the windscreen washer tank and the low speed fan relay is in the main fusebox. The 40A fuse for the fans is next to the NS suspension turret, beside the maxi fuse box.

Both relays are switched by the ECU, yes.

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#1612592 - 04/12/2017 19:42 Re: Widget displaying 2 faults [Re: Edinburgh]
GrahamL Offline
I need some sleep

Registered: 17/12/2005
Posts: 3471
Loc: Pothole City
If the widget is only showing current errors it would be worth checking for errors manually occasionally as well, with the terminal version.

The crank sensor may occasionally give an error but if it then gives 2 good timing pulses in a row then the error isn't flagged as present. That's what was happening with mine, engine never cut out or failed to start and dash warning light wasn't on but there was a crank sensor error stored. Cleared the error and it appeared again a few weeks later, so replaced the sensor and error never appeared again.

So the crank sensor can be failing without causing a problem or flagging a present error with the warning light, but you wouldn't know unless you occasionally scan for codes manually.

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#1612614 - 04/12/2017 22:49 Re: Widget displaying 2 faults [Re: Edinburgh]
Edinburgh Offline
Club member 225
Je suis un Coupé

Registered: 04/03/2007
Posts: 9957
Loc: Auld Reekie
Thanks for the replies chaps. I haven't had a recurrence of the widget display faults since yesterday and the widget is operating as normal - that is to say occasionally the standard parameters take a few minutes to show up while it "sets" itself.

I haven't had the engine temperature up high enough today either for one reason or another but I'll allow it to do that tomorrow under supervision. comparing widget water temperature readings and dashboard dial readings.

I'll also check the two relays as I have a/c, and the 40A fuse. In addition I'll need to connect the widget to my laptop to look for any more info.
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#1612733 - 08/12/2017 00:57 Re: Widget displaying 2 faults [Re: Edinburgh]
dante giacosa Offline
Club member 1447
My life on the forum

Registered: 25/05/2012
Posts: 1787
Loc: Going North on the A9
okay then-

tonight saw an investigation of the rad-fans 2nd speed relay, under the cover on top of the washer-fluid reservoir.

A quick poke about revealed the 85 / 86 coil-pair of the relay to be longitudially aligned with the car, and that the rear-most terminal was constant 12V (ignition-switched (+)). The forward-most terminal would of course be the negative switched from the ECU to bring in the fans.

Well, with the car cold & off, but with the ignition on, we tried & tried & tried to bring in the relay, with a ground-link to chassis, on the forward-most pin, but without success.

We retrieved the relay indoors and confirmed both the operation of the coil, and the functionality of the N.O. terminals.

Returning to the car, once it was throughly warmed through after a good run, we retried the test with a swapout relay (from another car) and it worked!
So the legacy relay was swapped back in too- and it worked also!(?).

Indeed, with the relay slightly raised on the base-socket, it was possible to poke the forward-most coil-terminal with the ground link wire, actuate the relay, and bring in the radiator fans.

Complete functionality.

Yet with the car cold, this wouldn't work. Either way however, this does not explain why the radiator fans have not been brought in by the ECU.

But it does verify the fans themselves, wiring to them, and eventually the 2nd speed fan relay.


Edited by dante giacosa (08/12/2017 00:59)

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#1612734 - 08/12/2017 01:04 Re: Widget displaying 2 faults [Re: Edinburgh]
GrahamL Offline
I need some sleep

Registered: 17/12/2005
Posts: 3471
Loc: Pothole City
<deleted wrong info>

Maybe the water temp sensor is just reading a bit low and needs replaced.


Edited by GrahamL (08/12/2017 10:07)

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#1612740 - 08/12/2017 07:39 Re: Widget displaying 2 faults [Re: Edinburgh]
dante giacosa Offline
Club member 1447
My life on the forum

Registered: 25/05/2012
Posts: 1787
Loc: Going North on the A9
Oh!?

that's strange then, Graham- because the 1st speed fan relay couldn't have been engaged- otherwise the fans would have already been on, surely..?

I thought they both had the capacity to feed the fans, and they each received a separate feed from the ECU, but one of them went through the 1st speed load resistance, bolted to the rest of the radiator...

However- I shall defer to your judgement.


It is maybe worth noting;
that initially trying to actuate the relay 'on the car', was to make use of the nominal 12v available with the car off, and 14+v available with the car running.
Only once in the house, with a 15 / 16v supply did we actually successfully get a result.
And then afterwards, did it work on the car.

I wonder if we have a sticky relay.

swapping the water temp sensor is a great idea; yes.


Edited by dante giacosa (08/12/2017 08:13)

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#1612743 - 08/12/2017 09:18 Re: Widget displaying 2 faults [Re: GrahamL]
Edinburgh Offline
Club member 225
Je suis un Coupé

Registered: 04/03/2007
Posts: 9957
Loc: Auld Reekie
Originally Posted By GrahamL

Maybe the water temp sensor is just reading a bit low and needs replaced.


Which is admittedly one of the original faults flagged up by the widget smile

Think I'll invest in one - IIRC the green top sensor (for my 1996 model) which goes in the thermostat......
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#1612744 - 08/12/2017 09:20 Re: Widget displaying 2 faults [Re: Edinburgh]
dante giacosa Offline
Club member 1447
My life on the forum

Registered: 25/05/2012
Posts: 1787
Loc: Going North on the A9
No. 61 on the schematic.

Graham- would it be accurate to say the car has two temperature senders..?

The schematic appears to show a single-pole version just for the gauge on the dash- but there must be the other one (you described) for the ECU, yeah..?

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#1612745 - 08/12/2017 09:24 Re: Widget displaying 2 faults [Re: Edinburgh]
dante giacosa Offline
Club member 1447
My life on the forum

Registered: 25/05/2012
Posts: 1787
Loc: Going North on the A9
got it- No. 28 on the schematic

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#1612746 - 08/12/2017 09:58 Re: Widget displaying 2 faults [Re: dante giacosa]
GrahamL Offline
I need some sleep

Registered: 17/12/2005
Posts: 3471
Loc: Pothole City
Originally Posted By dante giacosa
I thought they both had the capacity to feed the fans, and they each received a separate feed from the ECU, but one of them went through the 1st speed load resistance, bolted to the rest of the radiator...


Yes, you're correct, not sure where I got that idea from. smile

In the diagram it actually shows that the relay in the fuse box only switches on one of the fans at low speed, but the one at the washer bottle switches on both at high speed. In reality I think both activate at low speed or high speed, don't they?

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#1612747 - 08/12/2017 10:03 Re: Widget displaying 2 faults [Re: dante giacosa]
GrahamL Offline
I need some sleep

Registered: 17/12/2005
Posts: 3471
Loc: Pothole City
Originally Posted By dante giacosa
Graham- would it be accurate to say the car has two temperature senders..?

The schematic appears to show a single-pole version just for the gauge on the dash- but there must be the other one (you described) for the ECU, yeah..?


Yes, the single pin sensor is only for the dash gauge, the 2 pin sensor is the one read by the ECU.

The earlier cars have 2 sensors, with the single pin sensor in the side of the head and the 2 pin sensor in the thermostat. Later cars just had a 3 pin sensor in the thermostat but it worked in the same way, with 2 pins for the ECU and a single pin for the dash gauge.

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#1612749 - 08/12/2017 10:25 Re: Widget displaying 2 faults [Re: Edinburgh]
Edinburgh Offline
Club member 225
Je suis un Coupé

Registered: 04/03/2007
Posts: 9957
Loc: Auld Reekie
Ok, just had a chat with Steve at AA, he assures me the green-top sensor mounted on the stat is for the ECU, and the other temp sensor (probably mounted on the block, but for which he never receives any requests) sends info to the dash gauge.

He logically asked whether I'd changed the stat in the last 2/3 years as they can fail in open position and send all the wrong messages to engine management - I've had this happen a couple of times in the past and would say fairly confidently that the stat is still doing its job

......but wait shocked.......

In the last couple of days I was surprised to feel how little heat was coming from the block itself even after having run up to 102C ...

I'd better do the hose test....


Edited by Edinburgh (08/12/2017 10:26)
Edit Reason: just missed Graham's post
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#1612750 - 08/12/2017 10:34 Re: Widget displaying 2 faults [Re: Edinburgh]
GrahamL Offline
I need some sleep

Registered: 17/12/2005
Posts: 3471
Loc: Pothole City
Maybe you have a bad connection at the control box on washer bottle. It has a flexible pcb inside and the tracks + solder connections can go bad + the relay socket contacts themselves can corrode.

Had similar with the socket for the aircon compressor relay in that control box, was intermittently not working but if the relay was wiggled around a certain way it would work. I cleaned the relay contacts in the socket with a very thin file and it's been fine since.

This one:

http://www.boots.com/boots-sapphire-nail-file-10234966

cut down to fit the pin socket like this:

click to enlarge

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#1612753 - 08/12/2017 10:54 Re: Widget displaying 2 faults [Re: GrahamL]
Edinburgh Offline
Club member 225
Je suis un Coupé

Registered: 04/03/2007
Posts: 9957
Loc: Auld Reekie
Now that's interesting Graham as the relay itself "looks" brand-new with shiny pins, but during testing DG's trusty implement was inserted several times into the sockets which may effectively have cleaned up some internal corrosion.....
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