2010 1.8 transit connect radiator fan fault

[H_O_D]

Hi, been searching through the forums but not found anything definite, any and all advice appreciated:

UK Van 1.8 tdci, overheating, needs a head gasket, getting ready to do it in the next few weeks: radiator fan never runs when the temperature gauge is over half way or the overheating warning is on. Fan motor was seized so replaced.
Fan comes on with for scan on high only, no response from low command.
Both relays for high and low work, both have power.
Jumping low or high relays in the fuse box operates the fan at low or high correctly (resistor therefore seems ok, visually inspected and has continuity).

Question is, if the temperature gauge is reading correctly is there a problem with the pcm, the wiring in-between the sensor and the pcm or relay to pcm. Anyone any experience of this? I'm presuming the temperature sender is good as the gauge works, is there an oil temperature sensor as well? Bit stumped, don't want to fix the gasket only to cook it if the fan doesn't work.

Thanks

[metalworker0]

not sure if it has two sensors ..one for the gauge and one to put the fan on.

one is in the end of the head by the air filter box, other one is in the thermostat housing ..not sure which is which


all the best.mark

[H_O_D]

Thanks Mark I'll have a look at the thermostat sensor. The cylinder head one definitely does the gauge in the dash. Cheers

[H_O_D]

Update, no thermostat sensor only the cylinder head one and the oil pressure switch above that.

[metalworker0]

Think you are going to be buying one of those cheap laser temperature thngies

I'm not recommending this one, as I don't know if its any good or not , it's the cheapest I could find, so link is to give you idea what I'm on about - EXAMPLE:

https://www.ebay.co.uk/itm/135077868908?


all the best.mark

[H_O_D]

Saw one in Lidl today actually might get one after all.

Turns out the radiator fan comes on full tilt but not stage one, which I think would help with keeping temps lower for longer. Temp send in the head causes full fan speed if it's unplugged too, failsafe mode I suppose.

Looks like there might be a loom or pin issue if there's no way to trigger low speed on command. Will update once I've sorted the oil leak and done the head gasket.

[metalworker0]

I've remember reading other posts here ..on this forum, talk about a resistor pack that sits on the back of the fan for the two speeds. full speed - it bypasses the resistor ..low speed it goes through the resistor.

search forum with two words ..fan resistor
..ignore posts that mention heater or blower

Anyway that's where you should focus your attention ..seems a common fault for it to pack up..

all the best.......mark