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1994 C68 problem

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Old Sep 15, 2010 | 11:42 AM
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Default 1994 C68 problem

The electronic climate control does not light up any charactors nor do any of the setting green lights light up. I've tried two other c68 units and still nothing. I've checked all the fuses in the side of the dash, what could be the problem? Thanks.
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Old Sep 15, 2010 | 12:35 PM
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Originally Posted by Y-ME
The electronic climate control does not light up any charactors nor do any of the setting green lights light up. I've tried two other c68 units and still nothing. I've checked all the fuses in the side of the dash, what could be the problem? Thanks.
Is the background lighting up, but no characters, or isn´t there any power sign whatsoever?

Done any other work prior to the malfunction?

On mine (91) the background LCD whas lit a little dim, but got no characters and no green lights over the buttons plus SYS in the speedo, turned out to be the first fuse (blue 10 amp top left) was out, just forgot about it when I had the doors open working on something else.
In the pass-side fuse-holder, there are 2 fuses, ctsy and AC, and under the hood, on the RH side there is a 5 amp fuse near/between the blower motor and the washer tank.

This is on the 91, can... be the same on the 94.

Hope it helps.

Last edited by vette079; Sep 15, 2010 at 12:42 PM.
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Old Sep 15, 2010 | 02:03 PM
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Originally Posted by vette079
Is the background lighting up, but no characters, or isn´t there any power sign whatsoever?

Done any other work prior to the malfunction?

On mine (91) the background LCD whas lit a little dim, but got no characters and no green lights over the buttons plus SYS in the speedo, turned out to be the first fuse (blue 10 amp top left) was out, just forgot about it when I had the doors open working on something else.
In the pass-side fuse-holder, there are 2 fuses, ctsy and AC, and under the hood, on the RH side there is a 5 amp fuse near/between the blower motor and the washer tank.

This is on the 91, can... be the same on the 94.

Hope it helps.
The orange background does light up, just no charactors or indicator lights.

I pulled and looked at every fuse. I've seen the one between the blower and tank on earlier cars but can't find one on this one.
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Old Sep 15, 2010 | 02:12 PM
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Does SYS blink in the speedo?
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Old Sep 15, 2010 | 04:15 PM
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Originally Posted by vette079
Does SYS blink in the speedo?
Sure does, but my battery was dead this morning as I left the key in it and turned.

Also now it seems the lcd does not light up, just opposite of what the climate control is doing.
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Old Sep 15, 2010 | 04:23 PM
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Originally Posted by Y-ME
Sure does, but my battery was dead this morning as I left the key in it and turned.

Also now it seems the lcd does not light up, just opposite of what the climate control is doing.
You mean the speedo LCD, don´t you?

I would charge the battery up full, just to verify if the SYS blinks in the speedo LCD after you turn on the ignition.

If it does, it shows the exact same symptom as mine, and that was a ctsy fuse not in place.

In that case, try swapping fuses (same amp) to see if it changes.

If it doesn´t, question mark from my side.

The FSM shows a trouble tree, but a bit long to post here.

Better to see if you can borrow or buy one for your year in that case...
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Old Sep 16, 2010 | 12:39 PM
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SYS still flashes, I switched out both courtesy fuses, still no Bueno.

I have a 93 service manual, it has nothing on diagnosing a non displaying control unit.
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Old Sep 16, 2010 | 01:23 PM
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Originally Posted by Y-ME
SYS still flashes, I switched out both courtesy fuses, still no Bueno.

I have a 93 service manual, it has nothing on diagnosing a non displaying control unit.
Is the 93 FSM a single or a double version?
The 91 is double (separate electronics diagnose, a thinner book).
In that one there is a diagnose section on the C68, at page 8A-62-5.

Is there at least one thing working on the AC/heater, or is it completely dead?

One other thing you can try is to disconnect the battery for 15 secs and reconnect to see if it makes any difference.
Tip from the FSM.

Last edited by vette079; Sep 16, 2010 at 01:29 PM.
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Old Sep 16, 2010 | 02:56 PM
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It's the double, I'll check the smaller half.

The controls are completely dead nothing works.

Battery disconnect does nothing.
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Old Sep 16, 2010 | 03:36 PM
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Originally Posted by Y-ME
It's the double, I'll check the smaller half.

The controls are completely dead nothing works.

Battery disconnect does nothing.
Yep, it´s explained in the smaller one.

BTW, the horns still work...

IIRC, I bought them from you some time ago, last year I think it was.
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