Temperature, gauges, intrument panel, fans and blocked drains... help please

[benturner]

Hello all,
I've owned my 2002 Mk1 1.8 T 20V (94K miles) for just over a week and have a few faults I'm hoping you can help me with. Any ideas would really help. I haven't been able to find exactly what I need in previous posts.


1. Temperature gauge and fans - My temperature gauge (on the instrument panel) only works intermittently. It usually doesn't move above 60degrees (the minimum on the dial) but has worked once in the last 10 days. Loose connection? Damaged gauge? Dodgey sensor? Which temp sensor is used for this? Can I access it to test the connections?
Extra info:
I have been able to read the coolant temperature using OBD2 and the Torque android app.
During a run from cold the temp came up to 90-97 degrees C. While driving the radiator seems to work as the coolant temperature reading (from Torque) goes down to 65-80 degrees. When idling it goes back up to 90-97 degrees. My radiator fans did not activate at 97 degrees. Should they?


2. The instrument panel LCD (clock and journey distance) loses it's memory when ignition is switched off. The lifetime mileage does not get erased (I imagine this does not rely on a 12V connection to avoid loss of the important data). I have a good understanding of electronics although I'm not very experienced with cars and repairs.


3. Rain drain holes. How can I access the drains under the windscreen please? I think the driver's side is leaking onto my pedals in heavy rain.
Extra info:
I have recently re-sealed all door panels using the advice from this forum which seems to have stopped all leaking from these areas. Carpets are drying slowly and I have moisture traps in place removing humidity.


I really hope I can iron out these troubles so I can enjoy this car with a bit more faith and confidence in it.

Thanks in advance everyone

 

[Smurfy]

Hi,

I had the same temp gauge issue as you when I got my Cupra TDI, mine needed a new Thermostat fitting which resolved the issue.

I think the mileage resetting must be how its programmed as mine does the same, does it with the MPG figures as well, only does it for that journey, and depending on how long your out of the car will include the next journey as well.

And the 3rd query, I would assume that you need to remove the plastic trim at the back of the engine bay under the windscreen to get to this, but not sure tbh.

 

[Smurfy]

Just had a look through my user guide, and if you press the reset button, the number in the top left of the trip computer should change to 2 and this shows averages of a combined journey of up to 100 hours.

 

[Seal_LCR]

Thermostat and coolant sensor could be at fault I'd change both which I did as they are t expensive

 

[addavis89]

Drain holes are under the windsceeen scuttle panel.

 

[benturner]

Thanks everyone for your quick replies.

1. Coolant temp gauge - I can't believe the temp sensor is the reason my coolant gauge isn't working for the simple reason I get a temperature reading when connected to the ECU via an OBD2 bluetooth adapter and Torque app on android. The temp being read by the ECU seems to go up and down with normal sounding figures. It does get a little high at idling (90-98 degrees) but I think this may be down to a fault with the radiator temperature switch or the rad fans.

2. I'm certain the clock and mileage display is faulty and not the intended operation. It certainly shouldn't reset everytime I switch off the ignition.

I'm thinking there may be a wiring issue with the instrument panel in which the constant 12V feed needed to maintain clock memory is absent (hmm maybe a sneaky fuse somewhere?!). Perhaps this is also linked to the temperature gauge.

3. I better get my gloves on and start scooping out a world of crap that must be blocking those drains.

More investigation needed. There goes next weekend! :S

 

[paul6316]

The coolant temp sensor sends two readings I think, one being to the gauges. Change the sensor before you do the stat and it may cure it. Costa about a tenner and is a five minute job.

 

[LEE69]

3 might be where the wiring loom enters the car under the scuttle panel, they used the shite seal on it as the door regulator panels

 

[LEE69]

The coolant temp sensor sends two readings I think, one being to the gauges. Change the sensor before you do the stat and it may cure it. Costa about a tenner and is a five minute job.

Yeah one to the gauges and another to the ecu.

 

[Muttley]

The trip computer has two sets of registers. One (set one) resets after the power has been off for two hours. Designed to accumulate the readings for a journey that may be interrupted by a stop for a meal.

The other set (set two) carries on accumulating mileage/mpg/time/average speed until reset manually.

Toggle between the two sets by a brief push on the reset button, at the bottom of the wiper stalk.

The coolant temperature sensor package contains two separate sensors, one that just feeds the dash gauge and another that feeds the ECU.

 

[benturner]

Ok thanks everyone for your advice. I've now had a good flick through the ELSAWIN circuit diagrams and MK4 golf Haynes manual after reading your advice.

1. The temp sensor/sendor does indeed have 2 thermistors in it. As you very clever folk pointed out, 1 is for the ECU and 1 for the gauge. Makes sense really because if 1 fails at least either the ECU or gauge can raise the alarm if overheating.

I measured the resistance of both thermistors. The ECU thermistor (pins 3&4) had 800k ohms but the gauge sender thermistor (pins 1&2) showed as an open circuit so therefore damaged. New one was 12 quid

The rad fans weren't coming on at high idling temps so I shorted out the rad thermo-switch to see if they'd work. Fans are fine so bought a new thermo-switch.

2. Trip computer. I realise you guys are talking about the trip computer I had in my mk4 golf. My mk1 2002 cupra T has the older trip computer with simple single button on the instrument panel. Twist to change time or press to reset trip mileage are my only options. The clock resets too when ignition is off so must be a simple fault in there somewhere. Maybe its a simple fuse on the 12v feed.

3. I think it is that stupid crap foam sealant they used around door cards and wiring loom entry points. It's almost like those Spanish engineers weren't expecting rain. Clearly never been to north Somerset!


I've decided to have a full service done and ask local garage to fit the temp sensor and thermo-switch. Also getting the P0411 engine fault code now. I think my secondary air pump is dead so may ask them to repair/replace it.

Thanks everyone again for your time and thoughts.
Cheers

 

[matt_s]

Is the secondary air pump making a noise like a hoover and giving a low flow fault? If so you can drill out the rivets and put nuts and bolts in their place.

 

[benturner]

I can't actually hear anything from the pump but yes I do have the P0411 incorrect ssecondary airflow detected fault.

I tested the voltages on the electrical connector for the pump and it seems 12V is present for the first 50-60 seconds after cold start and switches back to 0V after that. That seems to be what it's meant to do.
I took off one of the hoses but couldn't feel or hear any flow during that time.

It seems to me like the car's trying to power the pump but nothing's happening...maybe it has a dodgey ground connection? Hmm confused! It can't be the fuse or the relay because I was getting 12V at the pump electrical connector. Or could it?!

 

[matt_s]

That sounds like a dead pump. You can just replace it with a resistor and a blanking plate to save the cost of a new pump. It's only there to help the cat warm up faster when it's cold.

 

[benturner]

Changed the engine temperature sensor today and the temp gauge in the instrument panel works again..... yay!

 

[benturner]

I've ordered a 29mm deep socket to remove and replace the radiator fan temperature switch. That's a job for next weekend.

 

[benturner]

I changed the radiator fan temperature switch today and it made no difference. The fans switch on when the Air Con is activated but the temp of the radiator seems to make no difference to fan speed. With my OBD plugged in I let it the engine idle until it got to 107 degrees and the fans did not switch on at all.
At the moment I make sure I have AC on when idling to ensure the fans will blow at least some of the time to avoid overheating.

Any ideas as to why the radiator temp switch may not be activating the fans? There is definitely 12V present at the electrical socket.

 

[mutant_matt]

Have you tried the test of the fan harness? (which is usually used to infer that the rad fan themostatic switch needs replacing).

The one where you take the plug off the fan switch and short pins 1 & 2, to check for low fan speed running (switched on by the thermo fan switch), then short 2 & 3 with the ignition on, to test for the high speed running.

Just a though? If *that* does work, you'd assume it's a faulty fan switch (unlikely, as you've replaced it), so I guess the Fan Control Module is left as the likely culprit.

HTH!

Matt