Supra 950

[mattym]

my colleague was called to a Supra 950 not lighting up it was bought into the workshop and checked by me, i was not getting voltage on 1j12 (i cant remember the na,es of the terminals) but i was getting voltage to 1j15 and 1j8 could some1 please advise me on what could be wrong i placed a link into 1j12 and positive the unit failed to start but the controller lit up but would not switch on or off any help is appreciated thanks

[cadwaladr]

have you checked the auxillary feed at the battery this wire can break.

[mattym]

i think it is mp+ and that seems ok where in the control box dpes the auxillary wire go

[cadwaladr]

is fuse f2 good does it have power

[cadwaladr]

have you checked the cable between in cab and unit have seen many rubbed thru,best way is to unplug both ends and do a continuetty test[sorry about the spelling]

[cadwaladr]

there is a switch on the unit which behind the control panel which could be in the off position or broken[its use is for when working on the unit you can turn it off to save running down to the in cab.

[mattym]

all fuses etc are good and the incab witing is also good started pulling my hair out now

[cadwaladr]

does the switch up top work and do you have battery power to the control panel upstairs?

[froggy]

in the control panel is a small plug that runs up inside cab control loom one plug goes to micro there is an earth in control box bolted to the bottom and a small plug with a green and white wire link the two green wires and see if it run if it does cab loom u/s

[IRMechanik]

The rocker switch in the cab command itself have been known to fail, depending on how much coffee has been spilt into it.

from your description it does sound like a problem in the cab command or wiring to it. If you have power to 1J8 with the switch on, the cab command is not providing ground for the run control relay.

[mattym]

checked all of this it is all ok when i put 12v from the relay board and link it to 1j12 the cab command powers up but the on off switch deos not work on the command, i have also tested the engineer switch and this is fine, a colleague suggested a cab command but i cant see that, due to it not getting power to the micro on 1j12 any more ideas is greatly appreciated

[IRMechanik]

the cab command controls the rcr (run control relay) by applying power to 1J12 you are bypassing the rcr. The RCR gets power through f2 from the master on/off switch. Power at 1J15 and F2 confirms this good. The cab command switch controls the ground for the RCR. Power at 1J8 with the switch on confirms the rcr is not getting a ground. When the RCR closes power is sent to the micro via 1J12. There is also an option of a door switch relay on the rcr circuit that could be a problem as well.

[mattym]

i will try a cab command today and let you know how i geto on thanks for the help guys

[mattym]

IRMechanik
You were correct the cab command was at fault, thanks very much, i was under the impression that 1j12 was permenantly 12v and the relays got feeds from that, is there a easy way to read the Carrier wiring diagrams because nobody has ever showed me

[IRMechanik]

Carrier schematics are lousy at best they neither represent a logical flow of power (positive on the right negative on the left) like a schematic should or an actual representation of component location, like a wiring diagram. They are closer to a schematic because they don't even try and show actual component location. The relays are generally shown in two parts the coil (round circle with the component acronym in the middle and pin numbers on either side) and the the actual contacts are shown somewhere else (two lines for no open contacts, two lines with a slash for nc contacts). Could be in several places in the case of multiple contact relays.

work with them long enough, you'll get used to it. TK wiring diagrams and schematics are much better.