Rover 75 M47 2 speed fans
 

I apologise if this has already been covered, but the fan on my car is not working. I have removed it from the car in the hope of finding the problem. It has a gold resister showing continuity as do all the wires from the pugs to the control box apart from the thin blue one which has intermittent continuity.I am hoping that is the problem. The fan itself runs if connected directly to 12v. I am no electrician and would struggle with any wiring diagrams, but I understand the thin wires control the relays. I would like to know what colour wire controls what.

Many thanks in advance.

Here you go Jonathan:

• Black = battery negative
• Blue/red tracer = control signal, ECM to fan PCB.
• Yellow = + 12v
• Slate (grey) = earth from medium pressure trinary switch.

Simon

I will have another look tomorrow, I work shifts

Hi, I looked again this morning, from the control box the blue/slate wire does not connect to anything outside the control box, just terminating at the rubber wire support. Lower down near the large engine plugs the grey/ slate wire connects to the blue/ red trace wire. Is this correct?

Thanks

Hi Jonathan.
Sound about right, as the control box of a PWM2 with resistor differs in the fact that the grey/slate wire is sometime connected in the control box.
https://i.imgur.com/ipOW8itl.jpg1

https://i.imgur.com/mBeNr0ml.jpg2

whereas sometimes they can be connected further up the wiring loom coming from the control box going to the large plugs, in the control box it shows the grey wire on it's own terminal but cut off as it exits the box.

https://i.imgur.com/ZEm321el.jpg3

On the M47 control box the grey wire is on it's own terminal but then passes through the control box to the large plug.
https://i.imgur.com/ncovUoKl.jpg4

Therefore it could be one of the relays, or most likely its the PCB board.

Could you add a few photo's of the wiring etc.

I will post some photo tomorrow as I'm at work at the moment. It does look like the third photo. I'm determined sort this out, many thanks for your help Arctic.

Hi, I am having trouble adding images using my phone, I’m not sure if its because I’m not a full member. Anyway the you say the PCB or the relays may have failed, the good news is I have saved the original three speed fan that failed on the armature after the brushes wore through. I have looked and the control box looks identical. I guess it’s worth a swap around. Also the 80 amp fuse and fuse 4 are good.
Thank you

I was wondering if any member would have the expertise to help me test the fan and help trace the fault. I am starting to think the fan might be ok and the fault may be on the car side.

Hi Jonathan.
Did you swap over the relays & or the PCB board from the other, fan? if so what was the outcome.

To be honest I read somewhere that the pcb can be easily damaged and so I haven’t tried that option yet. I was hoping that there may be a way to check the unit out first before I do so. I do not want to risk damage if it’s mot the fan at fault. I’ve tried looking at older threads but the photos are no longer available for some reason. I am going to turn my attention to under the bonnet although I could do with a bit more knowledge on what to check for connection wise lol. I know broken and chaffed wires can occur so I’ll be looking out for that.