Beautiful, and thank you Sir!
Now I (think I) get it!
1) When the temp/fuel gauges completely drop out, ie: they are receiving NO voltage input.
what we failed to mention also was
that when this intermittent failure occurs it is then followed by the "check radiator fluid" on the edu screen. I surmise then that what has happened is a loss of INPUT power to the edu 210 (when the gauges reactivate, the check rad fluid & "low fuel light" is part of the "start-up sequence" for the edu receiving power. IF the edu is not receiving 12v, THEN it can't send a signal to the fan relays. That's a problem...
Okay -- this is progress (unless I'm misunderstanding the wiring diagrams) in that now we know it's an intermittent power input to the EDU 12v
Although Scantar and I both drive CSE models we both prefer the analog clocks of the CD so would be unable to see if other edu outputs also all failed at the same time.
My intermittent temp/fuel power loss failure started after I'd done other work behind the dash cluster so I assumed it was my ribbon connection -- that was several years ago. And then it stopped happening so I figured I had a good connection again... but this past summer it started up again.
It would now seem to me that my OTHER intermittent temp/gas gauge failure where both gauges read high (accompanied by my voltage GAUGE reading low -- actual alternator output is fine) is an entirely separate failure issue -- although obviously still linked to the edu 210...
Chengny -- what I couldn't determine from your (alldata?) diagrams was from where the edu receives its 12v input? I'm guessing from the ECU but that's a dangerous assumption when dealing with SAAB...
So I guess while the gauge cluster/edu is out (or in my case -- before I bother to install my spare one) I can play with voltage inputs to the edu and measure what I'm getting on the gauge cluster. I can certainly check continuity between the connections but w/out a sillyscope (oscilloscope) one is really reduced to "swap-shooting" and hoping for the best...
I certainly have little faith in ordering a cluster/edu off ebay... One thing IS for sure -- the solder and connecting ribbons are fragile with age -- I would not really expect such a part to survive shipping...
Scantar (and everybody else) There is an easy fix for the power to the fans though. At this point we all have replacement radiators -- they all have the plug for the early MY 9K's that took a thermostatic switch to power the fans. Simply wire your fan through that as a back up.
automatic and manual have different criterion for the illuminations on the display, like automatic shows PRND321 for example and a manual would not, has the MPG instead or whatever, they're different is bottom line, its why I said you use the one specific to the transmission to your car. far as I know you need to use 1995-1998 EDU, though I don't know what year your car is as it's not in your avitar, 95-98 is where I have experienced the issue, the extent of my experience with it, there's 2 variants, manual and automatic EDU choose from years I described.Gauges dropping out today. Main beam indicator light still works as does the pictogram when both temp and fuel gauge don't.
What would happen if an EDU from a manual car was fitted to an auto or vice-versa?
You don't have one of those in line fuses on your 1997. Cooling fan changed in 1994, was the final year they did that, maaaaybee, 1995. Definitely not 1997. This is not your cure.This is a post from uksaabs.
"recently I was observing randomly the fuel level and the engine temp would just drop out, low water level warning would come on, then after maybe 30sec / min - the gauges would pop back up but not always to the correct position ( a bit of a pain ref: the fuel gauge) it would do this at random intervals - - the fix was - the 40amp fuse for the cooling fan had blown - - is this a weird and wonderfull SAAB signal of this failure ?"
I have a 1997 2.3 auto and 3 1997 2.3 manuals and 1 1995 2.0 auto.
As author of OG thread, I was talking about temp and fuel dropping simply to clarify as some other stuff popped in thread. I have 2 cars do this. Has nothing to do with ignition switch. Didn't want things confused. (I put a new ignition switch in for fun of it out of my stock and didn't change anything, had heard a rumor it might be associated). At one time I thought it might be a ground issue with headlight switch as well as that tied into ignition switch, doesn't have anything to do with that either from my findings.I tweaked with the EDU cables and connector when I had the fault and it worked. I rerouted the the Cables from the connector so they don't get pintch to the vent.channel. (and hopefully it will work).
Next thing to do is to resolder the EDU Power connectors in the EDU.
Maybe there are old and cracked.
So build a wiring harness to replace the ribbon connector?SNIP...
I still haven't associated a permanent fix. I have a suspicion it is the ribbon cable on the right. I have over 10 plus cars that are on road and haven't been able to dedicate the time to this retarded failure. I instead put my 9Ks in storage because it wore me out fiddling with it.
I'll continue to be interested in anyone thoughts on fixing the matter. Hardwire is the only way I can deduce to fix it, though haven't done the research on how to do that. Seems more complex then hardwiring a instrument bulb on a C900 for example. How do you hardwire a ribbon cable? The one on the right vertical side of cluster I believe is the perpetrator.