Wiring diagram for single fan M59

[Softweigh]

Hi Guys

Still struggling with the fan on my van ..I only have a big single fan in front of the radiator and it only runs a high speed and the only wiring diagram I have shows 2 fans ..I have been told that it uses a big resistor to run slow fan and hi-speed fan and I really need to get it working correctly. 

Any help would be appreciated

Chris

[Tomcat3]

Hi there have a read of this thread it may be of some use.
https://www.berlingoforum.com/thread-17223.html

[Softweigh]

Thanks Tomcat ... When I bought mine someone had hardwired 12v to the one fan relay ..based on it's speed it's the high speed relay ..so does the 2nd relay use the resistor and run the fan at low speed?? At the moment I run a cable that breaks the fast relay 12v connection so I can switch it in and out when needed but it would be far better to run the fan at slow speed and only switch to high speed when needed. Problem is also that both my fuel gauge and temp gauge are overreading by a huge amount and no-one seems to be able to repair them!!

[Sol]

Softweigh, have you tried DiagBox? Can't remember if you have it. The scaling can (I think) be adjusted on the gauges using that.

Also you can trigger low and high speed fan in there for testing, and it (engine ECU) can be programmed for dual speed or single speed fan. Maybe someone else has been messing with DiagBox before you got the van.

[Softweigh]

Thanks Zion .. Nope don't have it sadly I paid a while back to have diagnostic done .. took an hour and they said because someone had "hotwired" the cooling they would need at least 5 hours of a technician's time to trace and restore the wiring to original which would cost an arm and a leg! The only result they got from the diagnostic test was "one ECU relay faulty" .. They couldn't even tell me which relay and where is was located so that was a total waste of money!!

[Sol]

If you're handy with a computer you'd be better to get it you know. Saves a lot of guessing with these vehicles. Not expensive, and once you have it, no more cost for diagnostics

[Tomcat3]

The relays on the single fan set up is behind a cover in the fan shroud, the cover is sometimes just clipped on or some have a screw holding. This area suffers from corrosion so the relays could be past their best.

[Softweigh]

Thanks guys .. I think the problem is that because my temp gauge shows 100 C I'm expecting a fan to kick in (slow comes in at 97 and fast at 110 I think )... after borrowing an IR thermometer I measured various parts of the engine and top rad hose was 60 and bottom was 49 and the actual base of the temp sensor on the thermostat housing was still only 70!! Even though my temp gauge indicates 100 I don't think the temp sensor is sending the ECU anything that high so the ECU never sends a negative feed to either relay .. I think the previous guy saw the gauge going up into the 100++ area and thought the fans or ECU were faulty so hot wired the fan to run all the time. What the gauge says and what the actual engine temp is happens to be completely different. My relays are in a plastic box Tomcat 3 on the drivers side of the radiator and the cover has two self tapping screws so yes easy to corode '' I think I need to establish that the fans do actually come in at the set temps and take it from there. Once you have Diagbox on your computer what is the interface to the ECU and where exactly do you plug it in to start using it??

[Sol]

Ok so there should be a green and black 16 pin OBD socket, under the dash on the right in the M59 from memory (UK/AU driver's side) - the Actia 3 interface (the Lexia part) connects to that, and to the USB socket on the laptop. The diagbox software is installed on the laptop and the drivers for the Lexia etc to suit the USB socket it is plugged into (each time you move it to another USB socket it will reinstall a driver until it has "seen" all sockets, best to use one and stick to that)

Once it's installed, drivers and all, and plugged in to the laptop and OBD socket, turn on the ignition and start the software.

First thing is to select your vehicle from a menu with photos of the models, then run "global scan" which identifies the various ECU's and the BSI you have. Once the list is built, which can take a few minutes, you can click a controller such as Engine ECU and see any fault codes, clear them, or start diagnostics or configuration. There are live test sections where you can run fans, open and close windows, test ABS, measure airflow, fuel pressure, battery health etc as well as configuration sections where you can change equipment options like cruise control, central locking behaviour (all doors on one button push, or front doors only etc) - lots of stuff.

Just stay away from "Reset Controller" on any section, it isn't the reset you might think it is and removes all configuration coding.

I have a manual, which I have attached for you.

[Tomcat3]

So I take it you have aircon if the relays are under the cover on the offside of the rad, that means there is more sensors. The engine management system coolant temperature sensor is in the right hand end of the cylinder head in the thermostat housing above the hermostat and will have a blue or green wiring connector. This sensor controls temp gauge/fans/ ignition and ecu along with the air con system.