Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) 2005 US spec 3.0L Roadster - mystery connector

I'm having overheating problems. Surprise, surprise. The Roadster has a replacement aluminum radiator and nice SPAL pull fan... however, it doesn't seem to blow the gale that it should, given it's capacity to move air. So, I went under the hood and poked around, only to find a two pin, female connector at the front (top) of the engine. The two wires appear to be Brown with Red trace and Yellow with Light Green trace. Have looked at online wiring diagrams for the "Federal" Roadster (that I presume means - meets federal specifications), but cannot find anything remotely like it. Thoughts?

Can't help with connector but you could check if fan is wired for two speeds and the higher is working. Typically each speed has a relay and the low speed one brings a Ford resistor plug into circuit for rad fan.

Hmmmm, that's an interesting thought. I have only heard the fan in one operating mode (or off). I wonder if it is two-speed and the high speed is not working. I'd like the car to run cooler while the ignition is on, and probably need to fit a bypass to keep moving air and cooling even after the ignition is off.

http://www.talkmorgan.com/ubbthreads.php?ubb=showflat&Main=2497&Number=24637#Post24637

The 2005 Roadster has two speeds. (The photo above was lost in the Photobucket debacle but go to the last post and it's there). The relay bank is directly above the steering column under the dash on RHD cars.

Dave:

Thank you. Any ideas on how to test the fan to see if it has two speeds? Does it kick to a higher speed at some higher temperature? If so, if my is not working, I presume it would likely shut off when it hits that temp, right?

All I can suggest is to replace the relay. Make sure it's diode protected.

MOG37, yes the higher fan speed is to offset a higher coolant temp. If you are comfortable with electrics then breaking connection to fan itself and connecting it directly to battery should prove it works and can run at a higher speed than you are currently getting.

If this proves to be the case then maybe the high speed fan relay is faulty. Check with replacement. This relay is the first of a row of five similar size ones with low speed relay adjacent.

Each of the relays are triggered by a ground connection to relay coil (pin 85) provided by ECU and dependant on coolant temp. I suspect after the low speed one is triggered it remains on and with further coolant temp increase the high speed relay is triggered effectively by-passing the dropper resistor that limits fan to lower speed.

BTW this resistance described as "Ford cooling fan resistor plug" of rectangular shape should be found in loom close to fan connection socket, and a clear sign you have a two speed cooling fan system.

A few tweaks and the Roadster seems to be running well and not overheating - even in Florida's early summer heat!

A few quirks still... the temperature gauge changes + or - 10 degrees depending whether the headlights are on or off!! It's almost an instantaneous change. Must be some sort of short. A little concerning when I turned the lights on while stopped in traffic... only to see the apparent engine temp jump to Hot... not that the gauges are that accurate!

That will be the PCB. The power relays are built into it. Mine started playing silly sods with the lights off. I hard wired the lights as on.

Not a short but likely an extra unintended current path for the draw from headlamps which manifests as a voltage drop to the instrument circuits. As John suggests could be the troublesome PCB.

An important check would be to ensure voltage measured at headlamps is similar to that measured at battery with headlamps on, to ensure they are working as brightly as intended. If it's within say 0.5 volts then it might be easier to live with this situation rather than spending time and money sorting such an illusive fault.