[urq] Overtemperature Warning Light

[Tony Lum]

At 05:18 PM 1/2/2005 -0800, Alan Pemberton wrote:
>Having trouble understanding the Bentley.  There are two wires as shown on
>page 97.143 tracks 80 and 81 - one is blue/yellow and the other blue/brown.
>The blue brown wire is part of the coolant low temperature indicator system
>and this is working - blue light is on with engine cold.  The blue/yellow is
>shown continuing on track 243 which is blue white and connected to the air
>conditioning compressor clutch control unit? The indicator light is shown as
>K28 on track 185.

Hi Alan,

The overheat light bulb is also tested at startup.  When you turn the key 
on, the "61" line grounds the input line via the diode gate just above the 
ALT warning light.  After starting, the 61 line goes to 13 V or so.  The 
overheat switch on the back of the head enters the fusebox via pin C1 and 
comes out via D8 and runs to the instrument cluster at T10/2.  Its possible 
that your fusebox may have overheated and is shorted inside.  You could 
disconnect the pin at T10/2 to isolate the overheat circuit.  If its still 
flashing, it may be that the small circuit board plugged into the top of 
the instrument cluster is bad.  If the fusebox is suspect, probably you can 
see melting in the rad fan circuit fuse (no. 15).

HTH,




--
Tony

'80 5KS
83 urquattro #900302
'85 4kq
'87 5kcstq
'87.5 coupe GT