Gold resistor and P0481 error

[stevenkeyte]

I have replaced the original silver resistor with a gold resistor and prior to refitting the front bumper checked the operation of the fan, within 1-2 seconds of the engine (2.5l KV6) starting, the low speed fan commenced operation.

All cabling to the resistor was cable tied to the fan casing to prevent chaffing etc. and the resistor correctly secured in place, I tested the operation of the low speed fan several times prior to fitting the front bumper with no problems.

Refitted the front bumper and retested the operation of the fan to check correct operation, with no issues.

A couple of weeks later, put TOAF on the car to help track down a misfire on tick-over and the only errors showing in TOAF were 'P0301', the misfire and surprisingly 'P0481 Cooling fan 2 control circuit malfunction'.

Presuming the fan fault was a legacy fault from the previous resistor failure, I cleared the faults and re-scanned the car, both faults re-appreared, upon checking the fan visually through the front grille, sure enough the fan wasn't turning with the engine running.

Are there any other components in the fan control circuit to check before I remove the front bumper to investigate the failure?

Regards,

Steve

[T-Cut]

Hello Steve, if I understand you correctly, you expect the fan to run whenever the engine is running. Is that what you mean? If so, then you have it wrong. On starting the cold engine, the fan should run at low speed only if the aircon system is switched on. The fan is needed to cool the condenser. It should run continuously until the aircon is switch off. If the low speed resistor fails, the high speed will start after a short time and operate in short duration pulses as the aircon condenser trips it off and on.

The engine only requires fan cooling if the coolant temperature reaches certain trip temperatures. This diagram tells you how the fan should operate.


With the later 2-speed (resistor controlled ) system, I believe the old medium speed settings are provided by the second, higher speed fan.
I can't comment on the TOAF findings.

TC

[vitesse]

Toaf checks the operation of the original three speed fans. If of course you only have a two speed fan Toaf won't be able to find what it thinks is a missing third speed. Ignore it instead:

Go into the engine module, control, select cooling fan low speed move the slider to the mid-way position and press start, repeat with the high speed. If both activate then be happy.

As T-Cut says, the low speed fan should only activate if ACC is on or when the temperature reaches approx 104 degs, not within a few seconds of engine start.

Regards

[stevenkeyte]

Originally Posted by T-Cut

Hello Steve, if I understand you correctly, you expect the fan to run whenever the engine is running. Is that what you mean? If so, then you have it wrong. On starting the cold engine, the fan should run at low speed only if the aircon system is switched on. The fan is needed to cool the condenser. It should run continuously until the aircon is switch off. If the low speed resistor fails, the high speed will start after a short time and operate in short duration pulses as the aircon condenser trips it off and on.

The engine only requires fan cooling if the coolant temperature reaches certain trip temperatures. This diagram tells you how the fan should operate.


With the later 2-speed (resistor controlled ) system, I believe the old medium speed settings are provided by the second, higher speed fan.
I can't comment on the TOAF findings.

TC

Hi TC
It was my understanding that the low speed fan on the two speed set-up ran whenever the engine was running, from what you have written, it would seem this isn't the case, it will only run on engine start IF the aircon is enabled.

When I was checking the car with TOAF for the misfire, I had everything switched off (radio, aircon etc.) so it would seem that the system is functioning correctly, as when I'm driving with the aircon switched on, I no longer hear the high speed fan cut in and out, which it was doing previous to the replacement of the resistor, additionally, when I was scanning the car it was with a cold engine, so again, from what you write, the engine wouldn't demand cooling, which makes perfect sense.

I'll check the car next week when I have access to it (it's currently in the garage).

Many thanks for clarifying the operation for me,

Regards,

Steve

[SD1too]

Originally Posted by stevenkeyte

... and surprisingly 'P0481 Cooling fan 2 control circuit malfunction'.

Hi Steve,

RAVE gives the same code as TOAF when used with two speed resistor systems on a KV6. It's because "cooling fan 2", the medium speed on a 3 speed system, doesn't exist. Just ignore it.

Just to address a couple of points raised in the other replies ...

Originally Posted by T-Cut

With the later 2-speed (resistor controlled ) system, I believe the old medium speed settings are provided by the second, higher speed fan.

I'd expect the second "fast" speed (in the table) to continue to trigger at 112˚. Until then, the "slow" speed keeps running. After all, if a medium circuit still existed then there would be no fault code.
It's worth noting that the 3 speed system offers superior cooling control over the resistor system in this respect.

Originally Posted by vitesse

... the low speed fan should only activate if ACC is on or when the temperature reaches approx 104 degs ...

Just to avoid confusion it's 104˚ the 1.8 engine but 100˚ for Steve's KV6 and diesels.

Simon