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Instrument Panel Illumination Flicker

V

vetter1986

Guest
My vettes' dash lights will intermittently go out and comeback on. It sounds like a ground problem to me, possibly a connection at the printed circuit. Has anyone else seen this before?????
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
All at once......

Or just corners..... does the dash wig out as well ( bogus readings on all gauges?)

If you TAP the top of the dash.. do the lights come back on?
When the lights go out do the turn & Hi beam come on?
The typical problem isn't ground ( external ) of the dash but a crispy 12 pin molex style connector
internal of the dash module.

I need more info to help with this.

Mike
 
V

vetter1986

Guest
Dash lights flicker

It doesnt matter if you go around a corner or not there is no pattern to it. Sometimes tapping the dash will make them comeback but the gauge readings are fine. Thanks
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,237
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
About The Author
Gordon Killebrew retired from the Corvette Assembly Plant in Bowling Green, Kentucky in 1993 after 30 years with General Motors. After 17 years on the St. Louis Caprice Impala assembly line and occasionally on the Corvette line as a repairman, he went full-time on the Corvette line in January 1980 and then moved with Corvette to Bowling Green in 1981, working full time at the end of the line as a repairman. In 1988, he went to work in the plant's Action Center. The Action Center was the factory contact for GM dealers and owners to call and get their questions or problems resolved. He was also closely involved with the writing of Corvette service manuals, owner's manuals and dealer's service bulletins. He is the "Guru" of 1984-96 Corvettes and has written a book covering these problems and more of the operation and trouble shooting procedures on the 84-89 clusters. The book includes the part numbers for all the replaceable parts and is available from Gordon by calling 1-800-FY-VETTE.

Thank you for providing that link Mike, excellent article. :upthumbs

I met Gordon and bought his book when I was in Bowling Green earlier this year. I highly recommend it for any C4 Corvette owner with the digital dash. ;)

_ken :w
 
V

vetter1986

Guest
Dash lights flicker

Good info just what I was looking for thanks.
 

CorvetteArchives

Well-known member
Joined
Apr 19, 2001
Messages
549
Location
Carbon County, PA
Corvette
1984 Z51 Silver/Gray & as Much SS & CFibre we find
If everything goes out at same time.....yet functions properly when it does light........it probably is the ground
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
More good dash info

http://www.batee.com/corvette/index.html

75% of the dashes I've torn apart the right most molex pin has fried internal of the dash ( to much current from the 882's)

I've been moonlighting for a bit rebuilding dashes
84-89 and I've had more fun with this one, a few months ago I had a heck of a time getting my cruise to work...I got bad or incomplete info ( from dealers & mechanics) I found out very few people ( that I had contact with) actually understood how it did what it did. One dealer ( who shall remain nameless) stated "I had to replace all my LED's in the display" I got SO FRUSTRATED I built a car emulator....Two days later & one cobbled together vac pump I started reverse engineering the dash.
So far Ive fixed 12 dashes and have it down to a science. Call me crazy!

Mike
ps not to start a war... there are a lot of good mechanics out there in the real world... Just not out in Valencia!
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,237
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
One of these days...

Mike, when would be a good time for me to get in touch with you, or try to hook-up?

I think it'd be cool to meet and from the sound of your responses here, you have a pretty good handle on the digital dash.

My fix wasn't complete enough I guess; mine's acting up again. :(

_ken :w
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Dash Fritz!!!

Ken what's you dash doing???

Oh BTW
The starter circut is the following..

The (#5 Gauge) Yellow from the Ignition switch is the Start signal Pin S.

Which connects to

The VATS starter enable relay, Pin E (#5 Gauge),
*****behind the drivers information panel****
(Even though you VATS sensing has been bypassed the relay is still in circut)*****

Which connects to

The oppostie side of the VATS starter enable relay Pin A. The Wire in the circut is now a Dark Green with a white stripe (#5 Gauge) pin C

Which connects to

The Clutch Start switch Pin C Dark Green with a white stripe (#5 Gauge) swinger side of the switch.

Which connects to

The Clutch Start switch, Pin A, Purple wire,(#6 Gauge) The switch CLOSES with the pedal pressed.

Which connects to

A splice in the harness which supplies power to the CINJ/CLU fuse.
*****behind the drivers information panel****
and this supplies power to the cold start injector
via a small (.8) purple wire.The BIG Purple wire keeps going!

Which connects to

Firewall connector (C-100) the one under the brake booster.

Which connects to
The starter!Purple wire,(#6 Gauge).

My Guess is
A) The relay behind the drivers info panel is shot

Test Condition
CAR WON'T Crank!

Test
CAR IN NEUTRAL, Wheels chocked.

Put a 12 volt test light on the Dark Green/white wire( and to ground )

If the light LIGHTS the Starter ENABLE relay is ok.
If no light ( or dim ). Cut & splice those two wires together, do a NICE crimp connection & don't spare the tape.Yellow & Dark Green/White.

Next guess......

B) The clutch start switch is shot

Test Condition
CAR WON'T Crank ( Again )

Test
Put a 12 volt test light on the Purple wire( and to ground ) and press the clutch to the ground. You might want to check the mechanical adjustment while your under there.

If the light LIGHTS the Clutch Switch is ok.
If no light ( or dim ). The switch is KAPUT

If the light lights in either of these tests and the starter still dosent spin...it's the firewall connector.. but I doubt it.

Maybe this coming weekend..If you can hoof it to Valencia or E mail what time your going to be on here today.. I'll be on & Off today

Mike
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,237
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
Thanks Mike. It's funny, I was thinking this morning that even though I took notes last night, I'll never remember what you told me when I get around to working on it. Now that I printed this response, how can I forget? :upthumbs

_ken :w

(BTW, I be sure to give you plenty of advance notice when I head out your way. :L)
 
B

BasketCase

Guest
Hi guys, just thought I might toss in my 2 cents worth. I had the same intermitent lights out on my dash cluster, everything worked just no lights. I being in the restoration and upholstry field at the time bravely tore the dash apart and dove into the gauge cluster. I found that where the two circuit boards plug together there was a cold solder joint on the pin that went to the LEDs . I have heard that this is a common occurance on these dash modules. I resoldered the pin and perfection no more problem. Hope this helps
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,237
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
Gordon Killebrew specifically told me about that when I met him at Bowling Green, but of course I negleted (forgot :eek:) to dab a bit of solder in that area. I'll be sure to get it this time. ;)

_ken :w
 

bdreher

New member
Joined
Aug 5, 2016
Messages
2
Location
Alberta
Corvette
1987
instrument panel

My vettes' dash lights will intermittently go out and comeback on. It sounds like a ground problem to me, possibly a connection at the printed circuit. Has anyone else seen this before?????
i saw your post and i tried a few web links that other people posted but they are not working anymore....did you find out how to fix your dash problem because i have the exact same problem with my 1987 vette. and it goes off at any time not when i go over a bump, but if i tap the dash it comes back on...very weird
thanks BD
 

hcbph

Well-known member
Joined
Aug 30, 2013
Messages
260
Location
Minneapolis, Mn.
Corvette
86 Red Convertible
i saw your post and i tried a few web links that other people posted but they are not working anymore....did you find out how to fix your dash problem because i have the exact same problem with my 1987 vette. and it goes off at any time not when i go over a bump, but if i tap the dash it comes back on...very weird
thanks BD
Check over at Batee.com, there's a wealth of info there. Additionally, Bryan does repairs on C4 instrument clusters. Mine went out on my 86 the other year and I sent it to Bryan at Batee and had him repair it. Did an excellent job of it and it's worked fine ever since.
 

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