Diagnosing faulty cooling fans/relays/STOP light

[tigerstyle]

So recently my stop light has been flashing whenever the aircon is turned on, found this is a warning to let you know the cooling fans aren't running.

I've just pulled the coolant sensor from the side of the block (thermostat housing area) and then the passenger side fan runs at full speed, I read this is a normal safety default, but think both fans should be running 100% at this stage?


I can't get my multimeter into the sensor on the block to get an Ohm reading from it, as it's really tucked in there but the coolant temp is being reported as ok so presume it's working fully.

I've searched the problem a lot and the next step seems to be taking the bumper of to get to the control box for the fans, but don't want to jump in there right yet without a clear plan of what to check.

All under bonnet and under dash fuses check out as ok.

[cully]

if only one fan runs at full speed
none will run at half speed as it needs both fans in series to preduce the lower speed

i suspect either the fan thats not working is faulty or the relay that switches to series is faulty
the relays are between the fans in the triangle box

[tigerstyle]

Into the triangle box we go!

[Andy!]

not sure if there is a Bitron controller on the HDI like the petrol models but I would first suspect the wiring, a relay and then the fan.

if you fool your aircon pressure sensor (also disconnect your aircon compressor connector as I assume your AC is fooked) then you should be able to turn the fans on to series low speed using the aircon button when the engine is running.

The fan loom connector can get full or water and corrode.

[tigerstyle]

The aircon works perfectly thank you Serviced that last year.
I swapped the two green relays over in the triangle box and still only the passenger fan comes on, the black control relay tested fine and I swapped it with a known working wiper relay and still no change.

I think it's going to be wiring/earth somewhere or just a knackered fan.

Stolen from the GTi6 forum: This multiplug connector could be a suspect? This is the loom connector you mention Andy?



I don't know what other wires to trace back, but I've read an earth near the bumper mounts can corrode out.

[Andy!]

your aircon works! Christ!

in which case your fans should be coming on at low speed with the aircon (and engine on).

And yes, that is/was the connector in question. I fitted bullet connectors and wrapped them in plenty of tape on my P1.

[tigerstyle]

your aircon works! Christ!

New condenser and dryer and a regass last year, all DIY effort so not that much $$$ to do really!

I've kind of half packed the car up today, but really I should have removed the relays from the triangle box, and bridged the contacts in the socket directly to test each fan directly, just I need to 100% confirm which pins to short first

From this link http://www.peugeotlogic.com/workshop/wsh...fanop1.htm it should just be pins 3+5 with a decent thick wire?

[cully]

hdi fans are controlled by the ECU not a bitron box

[C2K]

I had exactly this a few years ago. It was a corroded pin in the radiator loom, it had completely disintegrated. I ran a separate 12V feed to the relay which was devoid of voltage, and hey presto sorted.

[tigerstyle]

ahhh cool, will probe with a multimeter tomorrow

[C2K]

My rad loom looked like this:

[Andy!]

there was a guys 306 that burnt out on pug306 just after he bought it from another member when driving in snow. When we looked into it this connector was suspected to be the cause of the fire.

[tigerstyle]

Luckily nice weather today so out again having a look at it.

Have found that both fans are working ok, bridge Pins 3+5 on the Left relay and both fans come on, bridge pins 3+5 on the right relay and just the right fan turns on (as expected)
Getting info from here: http://www.peugeotlogic.com/workshop/wsh...fanop1.htm

Took the rad loom off and the engine bay side connector looks mint, no corrosion there at all, so something is borked somewhere but?


**********************************
Reading here: http://www.frenchcarforum.co.uk/forum/vi...1&start=15

I think I should be getting 12V on pins 1+2 of the left relay at all times, I thought pins 1+2 are the low voltage contacts for the relay? or are they just 12V but low current contacts so still get the thinner wire? I thought they were 5V?

Either way I don't get any voltage there, so think that might be my problem, the thinner contact wires are broken... maybe...

[C2K]

I put that Peugeot logic thing in the FAQ yonks ago, it worked for me except that there was no bitron.

I didn't have any voltage at one relay altogether, so my fault was kind of obvious.

[tigerstyle]

Slightly similar here, I get the 'full' 12V going through the left relay (pins 3+5), but no voltage at the 2 switching points for the same relay(pins 1+2), so it gets power but can't turn on.
I need to multimeter out the rad loom connector and find which wires are the thin beige+pink wires and see if they are broken either the rad side or the car side of the loom.
So going to get one from the breakers to pull apart and make a test loom that way for continuity tests.

I can't think of another approach, and then if I find they are broken on the car side of the loom I'm still stuck or a fix, rip the whole loom open I guess ?

[tigerstyle]

Bizarre situation occurring here:

The Rad Loom is showing zero faults, and measure Zero Ohms resistance from every relay terminal connection to every pin. So is good.
The Engine Loom is giving out 14.4 Volts on Pin1 of the left relay (for low speed operation) Lights up a test light ok.
The connector looks mint with zero corrosion and is in good condition.

But I'm not getting the 14.4V at the relay end of the rad loom? Can only guess that there must be a tiny gap in the connector between the pins? But mechanically the connector seems sound?


(All fans and fuses+relays are working ok, I've checked the fans work on low speed by wiring the back of the relay directly to the battery for low speed, and pulled the thermoswitch and left the battery connection in for testing high speed too)