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Discussion Starter #1
Hi All

My car is a 2007 1.6 THP 150.

I've traced a "engine management system faulty" code to my intercooler fan not running. The error code I get is:

P0482
Additional fan under the bonnet control fault.
Permanent Fault, Open Circuit or Coherence.

If you're familiar with PP2000/DiagBox, you know it has a function where you can manually activate the radiator/intercooler fans for testing. When I activated the radiator fan, it runs on both low & high speed. But when I activate the "additional" fan (intercooler fan), it does not run. I've had a good look through the engine bay and the glovebox fuse box, checked all the fuses - they're all intact.

I unplugged the connector for the intercooler fan and manually hooked it up to the battery - it runs just fine, so the fan is OK. The issue must be with the wiring or the relays.

Where are the relays in this car? I can hear them clicking from within the dash when I run the test from PP2000/Diagbox but I can't actually see them..
 

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Having checked the wiring for this, the only relay showing is on the supply cut off relay which is drivers side if right hand drive car, under the headlight, that area, light brown relay.

The connection on that part that connects to the right hand fan is number 5 pin.

The wiring goes from the ecu splits to the right hand fan and also continues to the supply cut off relay.

The right hand fan as u will see only has 2 wires, positive and earth, the earth goes to an earth point on the front right hand side of engine bay, towards the wheel arch.

The connection at the ecu plugs is number 23 on the black connector IIRC.

So would try some continuity tests there, make sure the wiring is all secure, then would be looking at that relay.
 

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Discussion Starter #4 (Edited)
Ok.

I unplugged the connector that plugs into the fan right. I then connected the battery DIRECT to the fan - the fan runs. Then I put my multimeter probes into the fan connector. When I turned on the ignition, the multimeter shows 11v. When I run the actuator test, the multimeter shows 12v. I can definitely hear/feel the relay (the one under the headlight) click on and off.

Does the fact that the connector shows 11v BEFORE I run the actuator test but then shows 12v when I do the actuator test mean it is faulty?
 

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How are you testing the supply at the fan motor plug?

Is it with the multimeter leads plugged across both pins in the plug or with the ground lead of the multimeter connected to a body ground point on the car and the positive lead testing the motor connectors?

You should be using the second method with the multimeter using a body grounding and the positive lead individually testing BOTH terminals going to the motor, firstly with the ignition off, then ignition on and finally with the fan switch activated.
 

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So was speaking to a Peugeot tech about this and he had an interesting take on this and way to proceed, something a lot of Peugeot techs are now using.....

wiring a bulb in and see how bright it goes !!!!!

"The voltage down the wires will put pressure on the system and can tell you if a wire is corroded or partly broken.

Put wires each side of a bulb and plug one wire into one part of the plug and the other in the other side, run actuator test and bulb should light up, take note of how bright the bulb gets.

The brighter the bulb the better as the dimmer the bulb the more the flow is restricted by corrosion or broken wires.

Its if a wire is corroded or damaged it will always send down 12v, so you think its ok, but stick a bulb in the system it loads the system up which if a wire is damaged or corroded it wont cope with the flow it needs so the bulb will be dim"

worth a try !
 

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Discussion Starter #7 (Edited)
Ok I wired a bulb into the connector that is supposed to run the intercooler fan. The bulb won't go AT ALL.

Previously, with the ignition on I was getting 10-11v on the connector and when I ran the "Additional Fan" actuator test using Diagbox, I was getting pretty much bang on 12v.

With the bulb wired in, I get 0.00v with the ignition on, and 0.10v with the actuator test running.

I suppose this means there is something wrong with either the ground or the connection to the where the engine fusebox/BSI is.

There are 2 wires on this connector - one is a ground, and the other is yellow with green tracer. I presume I just find this wire in the fusebox/BSI area, then test it the same as I did with the bulb. I'll do this tomorrow... started raining just as I was making progress and I had to close up shop.
 

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Discussion Starter #8 (Edited)
Ok we have been making some progress (if you can call it that) but it's all been over PM, but I will post here incase someone else has these issues in the future.

The fault has been traced to the intercooler fan not running. The relay(s) seem to be OK as well so I am load testing the wiring. Load testing is done by taking out one of the headlight bulbs and connecting some wires to it and then basically making a circuit with the wires I want to test.

First, I applied 12V directly to the intercooler fan - it spins. So its definitely not faulty.

Second, I tested continuity between the ground pin on the connector that plugs into the intercooler fan. Continuity is OK, as is the light bulb.

I then removed relay 1524 (connector 4V NR) from the car, and tested ALL the wires from this connector. There are 4 pins on this relay, 1,2,3 and 5. I also removed the engine ECU so I could test right through the harness to the pins shown below. There are 3 connectors on the THP 150 that plug into the ECU. The ECU is immediately to the left of the battery. The connector I was using was the one closest to the front of the car.


Relay Pin 1 -> Engine ECU Pin 42 and Radiator Control Unit Pin 3.
Relay Pin 2 -> Engine ECU Pin 8
Relay Pin 3 -> Battery (+) terminal
Relay Pin 5 -> Engine ECU Pin 23 (This pin drives the intercooler fan)

All of these show good continuity and the light bulb also works. I only didn't put the light bulb through Pin 3 -> Battery (+) Terminal since this goes through the BSI so I didn't want to risk blowing anything up in there.

I also tested the fan connector.

Pin 1 -> Engine Relay Pin 5
Pin 2 -> Ground (on engine AND at Battery (-) terminal.

Solid connection again.

I gave all the above connectors a tug as I was testing them in case it is a bad connection but nope -- my test H7 load bulb stays lit solid and bright. I didn't notice any dimming at all.

I finally found the firing diagram - have attached. In this diagram:

1512 is the radiator fan ("left fan").
1511 is the intercooler fan ("right fan").
1524 is the supply relay under the right headlight (brown).
1522 is the radiator fan assembly resistor pack (top left hand corner of radiator).
1320 is the engine ECU which is located to the left of the battery
Connector 53V NR is the plug that goes to the ECU (the one closest to the front of the engine bay).

I've put everything back together since I need the car to get to work tomorrow... I did a quick road test but the fault is still there of course.

Any ideas on where to next?
 

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Discussion Starter #9
Today, I took the relay out and bridged pins 3 & 5 on the connector - the fan definitely runs.

Figured I'd bench test the relay. I took out the relay, applied power to pins 86 (1) an 85 (2), definitely heard the "click". I tested continuity across 87 (5) and 30 (3) - I have continuity an resistance measures 10-12 Ohms. I measured resistance across pins 86 (1) and 85 (2) - reads 71-73 Ohms.

I've read conflicting information on whether or not this really means the relay is bad. Apparently 10-12 ohms with the relay "on" is too high??

I'll see if I can source a replacement relay.
 

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Apparently 10-12 ohms with the relay "on" is too high??
12 Ohms over the closed contacts is WAY high. (85 86 is the coil, so about expected)

U=R*I

No idea how much the fan draws, but a mere 1A of current would drop essentially all the available (battery) voltage over the contacts, leaving nothing for a load...
Or put another way, you could short the output to ground and there would only flow about 1A of current.

Just measured a loose typical automotive SPDT relay, 30A capacity, pins 30 to 87a (the normally closed position). Shorting the probes of the meter together gives 0.8/0.9 Ohm on the display.
Measuring across the relay contacts (probes pressed firmly onto the spade terminals) gives 0.9 Ohm, so contact resistance probably around/less than 0.1 Ohm.
82.6 Ohm over the coil.
 

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Discussion Starter #11
Ok dare I say I’ve made some progress. After testing and getting really high resistance on those two pins, I found there was a quote a bit of oxidisation on them. So I got some fine sandpaper and went to work on it. Have a look at the photo for before and after. I put the relay back in the car, cleared the code and went for a drive - no DTCs stored and the AC works. Drove the car to work for a day and still no faults.

I’ll report back if anything changes. I’ll order a replacement relay anyways, they’re fairly cheap (£10).
 

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