glow controller intermittant

[VCurrey]

Am having intermittant glow plug control problems on a 1993 6.5TD 2500 S.C. Auto. It started out that the glows would not indicate on panel right away and then would after a little more time. Now they will only come on if I constantly recycle the ignition from 'off to start' until I can get them to "catch" on. So a set of contacts may be sticking? Any way I don't feel like spending $100 plus bucks unless I know for sure what the problem is. All the acg-9 plugs check out good and each draw from 13.3 to 13.7 amps full on (individually - short duration of course). Also I have been searching for a schematic for the controller in order to help me under stand whats going on in the circuit or to make a controller because they can't be that complicated. I'm mainly questioning the 'C' wire on the controller plug for the glow voltage reference measurement and where it goes and what it does - the rest is, as I stated, not too complicated; although I do have more questions on the thermister temperature sensor wondering if it is in series with the two coils for the idle control solenoids or in parallell with one - which would alter the resistance value considerably.
Sorry for the long explain - any input at all would be appreciated

[BobND]

90+ % chance the controller is bad. '93 is the last year of the autonomous controller. Later units, the controller was 'gutted" of it's control function, which was taken over by the PCM.

[VCurrey]

yeah, thats what I figure too - but I'm still determined to figure out how they work. Do you know if they can be taken apart or are they 'potted' with epoxy or something? Of course if they're like every thing else, if they can be dismantled to get at components; the components have the info scraped off so they can't be identified.
Thanks for input.

[BobND]

I've disassembled a number of those controllers. The circuit board is not "potted". Often, the relay portion of the controller has been "toast".

[VCurrey]

Thanks BobND: I needed that. I will definitely check it out after I get a reply to the next part of this reply.
Sorry to take so long for reply. I'm wondering now if the intermittant has something to do with the 'coolant level' switch/sensor because it has been flashing on before start(I don't recall seeing it flash on before start before - unless I just ignored and forgot about it) then it always stays off after start but yesterday I noticed it came on while driving close to home (I know that has not happened before). I disconnected the coolant level switch/sensor leads and reconnected and the lite still comes on before start but has not returned while running (so far).

[BobND]

The glow plug and low coolant circuits wouldn't have anything in common, except for the multiple ground points to the chassis and engine, from various ground leads in the wiring harness.