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Old 08-17-2004, 05:34 PM   #1
j3studio
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Default [85 LCD] The Dreaded Intermittent Electrical Problem

Sometimes, either when I've just started up or I've been driving for a couple of minutes, the LCD display on my 1985 will go completely blank. Everything else (at least everything else I've had the presence of mind to check while this is happening) keeps working fine. Sometimes the LCD display will give the impression that something is going on, but most of the time it is completely blank.

A couple of restarts later, the LCD display will magically start working again.

I looked in the 1985 service manual (I'm learning ) and the #1 troubleshooting hint for the instrument cluster is to check the LCD fuse, the CLSR fuse, and the G201 ground.

Some questions:

1) I'm assuming that it can't be the fuses since the LCD display works most of the time. Is that correct?

2) The G201 ground is said to be behind the instrument panel and near the left hand side of the steering column. I looked through the entire electrical diagnosis portion of the service manual and I can't for the life of me find a diagram that shows the location [there are diagrams that show G100, G101, G103, G104, G115, G116, G125, G140, G320, G400, and G401 ]. Is G201 hard to get to?

3) Am I missing something really obvious?


Last edited by j3studio; 08-17-2004 at 05:41 PM.
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Old 08-17-2004, 06:38 PM   #2
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I would check the fuse anyway, quick and easy. Maybe you should try checking the connectors on the display itself. this is not such a great job as you have to remove the whole display cluster. It has 2 connectors on the left at the back
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Old 08-17-2004, 06:49 PM   #3
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Thanks, Peter!

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Old 08-17-2004, 10:51 PM   #4
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Hey I've got an 85 that has the exact same symptons you describe... only problem is, about 3 or 4 days ago, it went black, and hasn't come back since... Maybe we could help each other on this... I've tried a ton of stuff trying to fix it... i haven't heard of the ground near the steering column though. I've checked (and cleaned) 3 other grounds related to this, and it hasn't helped. Have you search for this ground yet?
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Old 08-17-2004, 10:56 PM   #5
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Oh yeah- i just bought gordon killibrews' book on the digital dash. I was told it was excellent... do you have it?
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Old 08-17-2004, 11:54 PM   #6
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this sounds a lot like the ground problem... I would focus on that.
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Old 08-17-2004, 11:55 PM   #7
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Yeah, but where is that ground in the steering column? I had never heard of that before
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Old 08-17-2004, 11:59 PM   #8
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ah... that could be interesting... on TOP of the steering column, there are a multitude of wires connecting to the ignition system, signals and such. you may have to drop the column from the dash to reach them ok. A corroded connection could cause this problem.
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Old 08-18-2004, 12:12 AM   #9
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I agree that it sounds like a ground problem. This site has some good information on the digi dash. www.batee.com/corvette/index.shtml
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Old 08-18-2004, 12:27 AM   #10
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Quote:
Originally Posted by steveb
I agree that it sounds like a ground problem. This site has some good information on the digi dash. www.batee.com/corvette/index.shtml
yeah that sites good, and i've been all over it- but it makes no mention of this steering column ground... I've had some funky stuff happen to the dash while messing with levers on the column. I think you guys may be onto something...

Hey j3studio, have you tried anything yet to solve your problem? I'm interested to see if you've done anything i haven't
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Old 08-18-2004, 12:30 AM   #11
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G201 should be on the left kick panel. Remove the hush panel and then find the black support bar. It's either on it or next to it.

Doubt that's your problem though. This ground is spliced to a host of other stuff, so if everything else is working ok, this ground is probably good.

The other ground could be your problem. It runs to the ambient temperature overide switch and then out through the big connector behind the battery to the trans (upper left bolt for your year). As Killebrew points out, that connector can collect water in the base, where the ground passes through, corroding the contacts. His solution is to solder the grounds at the display - pins D1 & D3.

If you're going to remove the connector, take out the battery first. The upper half is the light circuits - all the engine stuff is in the bottom. Cleaning it can be a chore and some electrical cleaner that won't harm the plastic works pretty well. Smear dielectric all over everything and then Killebrew recommends that you spray it with undercoating after it's back together. Do make sure that the fresh air plenum drain tube is pointing away from it and the fusible links behind the battery.
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Old 08-18-2004, 12:38 AM   #12
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Quote:
Originally Posted by SunCr
The other ground could be your problem. It runs to the ambient temperature overide switch and then out through the big connector behind the battery to the trans (upper left bolt for your year). As Killebrew points out, that connector can collect water in the base, where the ground passes through, corroding the contacts. His solution is to solder the grounds at the display - pins D1 & D3.
fixed that ground (overide it), didn't help. Grounds in the display were soldered when i sent it away to get fixed. no dice
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Old 08-18-2004, 03:08 AM   #13
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Click the image to open in full size.

This right here did it for me. Once I soldered this extra ground on my 86 all my worries went away.

$200? Nope. Just replaced the bulbs and added one piece of wire.

Here's the page.

It might look complicated to some but it was relatively easy. Just keep unscrewing the IP until you get to the good stuff. I got so good I could get the IP out in my sleep. (Kept taking it out until I found out how to fix it, finally).

Nothing feels better than after putting up with an intermittent dash to know that it'll never flicker again.
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Old 08-18-2004, 09:31 AM   #14
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Quote:
Originally Posted by yellowlust

This right here did it for me. Once I soldered this extra ground on my 86 all my worries went away.

$200? Nope. Just replaced the bulbs and added one piece of wire.

Here's the page.

It might look complicated to some but it was relatively easy. Just keep unscrewing the IP until you get to the good stuff. I got so good I could get the IP out in my sleep. (Kept taking it out until I found out how to fix it, finally).

Nothing feels better than after putting up with an intermittent dash to know that it'll never flicker again.
That looks good, and if j3studio hasnt tried it yet he definitely should. But I seem to be having the same symptons his dash has, and I HAVE done that... and it didn't help
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Old 08-18-2004, 11:41 AM   #15
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I too had this problem in both 85's

I added the soldered wire like above and it worked great after.



Good luck
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Old 08-18-2004, 03:13 PM   #16
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Quote:
Originally Posted by mikey whipreck
That looks good, and if j3studio hasnt tried it yet he definitely should. But I seem to be having the same symptons his dash has, and I HAVE done that... and it didn't help
Have you also addressed the ambient temperature switch ground?
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Old 08-18-2004, 03:18 PM   #17
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Default Re: The Dreaded Intermittent Electrical Problem

Quote:
Originally Posted by mikey whipreck
Hey I've got an 85 that has the exact same symptons you describe... only problem is, about 3 or 4 days ago, it went black, and hasn't come back since... Maybe we could help each other on this... I've tried a ton of stuff trying to fix it... i haven't heard of the ground near the steering column though. I've checked (and cleaned) 3 other grounds related to this, and it hasn't helped. Have you search for this ground yet?
Mikey,

I haven't gotten to this yet - the engine is throwing codes again , so that's my biggest priority right now. I don't have Gordon's digital dash book, though that's probably going to be a Carlisle pick-up.
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Old 08-18-2004, 03:20 PM   #18
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Default Re: The Dreaded Intermittent Electrical Problem

Great stuff, everybody! Thanks a lot!

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Old 08-18-2004, 09:00 PM   #19
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Quote:
Originally Posted by yellowlust
Have you also addressed the ambient temperature switch ground?
Yeah i have... that was the first thing i tried... This has been driving me crazy... Thanks for the input guys... I ordered Killebrew's book a few days ago, and i'll try it again when I get it... I also plan on being at Carlisle, maybe i can get some more input from people that have been through digital dash hell
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Old 08-18-2004, 09:00 PM
 
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