Temperature Gauge Problems

[eeelie]

Hi

I have recently purchased a 1.6 Skoda pick up.

 

I have noticed the temp gauge barely moves above 70 deg, I have replaced the thermostat checking for the common damage on the end cover and also replaced the temperature sender unit but neither have made a difference.

 

I have two theories.

 

1- The interior of the pick up has defiantly been replaced and possible the instrument panel has also been replaced and now the temp gauge is no longer paired with the correct sender that was supplied via the reg number.

 

2 - The temp sender was a black 4 pin with blue ring and when I purchased a new one it was also a black 4 pin with blue ring, however when I check the Euro car parts website it suggest it should be a black 4 pin with yellow ring. The parts guy said they were the same?? Does anybody know if they work on different resistances?

 

Any help would be greatly appreciated, I have included a picture of my pick up and also a picture of the part number on the back on the instrument panel.

 

Kind Regards Nick

[RicardoM]

Both theories are most probabke. I will add a third: wiring. That includes the wires, the PCB, white connector to PCB, and the gauge itself (see photo).

 

In case you have basic electronics skills, I recommend a simple test (see photo) that will clear some unknowns.

 

Unplug the 4-pin connector and connect a 1Kohm potentiometer as shown to simulate the temp. sender. Turn ignition key to ON. Rotate the potentiometer from minimum  to maximum resistance. The temp. gauge should indicate from maximum to minimum temperature respectively.

 

We'll proceed according to results.

[topiarius]

This subject came up once before. The new thermostats don't seal properly and you need to use a bit of instant gasket. This solved it for me.

[eeelie]

Thanks for the replys.

I've put a potentiometer across pins 2 and 4 and changing the resistance I can make the temp gauge go fully up and down.

I going to try the instant gasket on the thermostat now, it's a nice easy job. I'll let you know the results.

[RicardoM]

I've put a potentiometer across pins 2 and 4 and changing the resistance I can make the temp gauge go fully up and down.

 

Ok. That proves the wiring is good, the gauge is good, but the resistance of temperature sender doesn't vary enough to indicate 90C when the engine is warmed up.

 

That leaves you with 3 options:

• the temperature sender is not paired with the gauge
• the temperature sender is defective
• the coolant doesn't get warm enough

A thermostat that 'doesn't seal well' only increases slightly the warm up time (let's say, during summer, from 7-8 minutes normally to 15 minutes).

A stuck open thermostat or no thermostat keeps the coolant temperature low for a much longer time depending on traffic and driving style.

 

If you want to test the temperature sender and have a proper thermometer handy, here is the temperature/resistance characteristic.

Edited 29 June, 2015 by RicardoM

[eeelie]

Ok, sealed the end of the thermostat into the housing cover, there was a noticeable difference in temperature of the hoses during warming up.

No change in coolant temp though. The needle is just past 70 deg when the cooling fan kicks in.

Any more suggestions?

[eeelie]

Thanks for the information Ricardo. I will investigate sender options and let you know how I get on.

Thanks

Ok. That proves the wiring is good, the gauge is good, but the resistance of temperature sender doesn't vary enough to indicate 90C when the engine is warmed up.

That leaves you with 3 options:

• the temperature sender is not paired with the gauge
• the temperature sender is defective
• the coolant doesn't get warm enough

A thermostat that 'doesn't seal well' only increases slightly the warm up time (let's say, during summer, from 7-8 minutes normally to 15 minutes).

A stuck open thermostat or no thermostat keeps the coolant temperature low for a much longer time depending on traffic and driving style.

If you want to test the temperature sender and have a proper thermometer handy, here is the temperature/resistance characteristic.

[RicardoM]

Thanks for the information Ricardo. I will investigate sender options and let you know how I get on.

Thanks

 

I would be interested in a similar table (well, 20C to 100C at least) to decide what sender is on your car now. That is, in case the sender is not totally faulty. What collar color has the sender? Any code stamped on it? What about the temp. gauge? Do you happen to have the code stamped on the lower part of the dial? See the photo in my first post. I'm trying to be methodical for a correct diagnosis.

 

One other thing. How long does it take now from cold start (engine temp. = atmospheric temp.) till the fan kicks in with the car just sitting at idle? No electrical loads, no A/C.

[nimbus]

Hello ,

 

I hope that i can post my question here; i have a skoda felicia 1.3 mpi from 2000 with 90 000 km.

 

My problem is that my temperature gauge didn't work, it's all the time at 0°.

 

So is my temperature sender dead? if yes, where is he on the 1.3 ? 

 

thanks for you reply.