digital dash in a 1990 Beretta problems

[gtuturbo]

(whitetalonb16g @ Aug. 04 2006,21:25)Q
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Ehmmm the resistor idea sounds good, any idea on what size or more info on this TSB ? I will do some searching to see what I can dig up.

Thanks for the info
Ask, and you shall receive...


Instruments - Fuel Gauge Blanks Out

[whitetalonb16g]

thanks for the link, but it is asking me to login and pay 24.95mth  

[gtuturbo]

Oops! Try this...

Instruments - Fuel Gauge Blanks Out


Number: 88-328-8C

Section: 8C

Date: SEPT., 1988
Subject: ELECTRONIC CLUSTER (U52) REPAIR

Model and Year: 1987-88 BERETTA, CORSICA WITH U52 OPTION
TO: ALL CHEVROLET DEALERS


This bulletin provides repair procedures for six (6) different conditions that may occur to the electronic instrument cluster used in 1987-88 Beretta, Corsica models.

1. Fuel Gage Blanks Out When The Tank Is Completely Full

Condition:
The fuel gage will blank out (show empty), and the pump symbol may flash, when the tank is completely full. When the level of the tank drops slightly (usually after 25 to 30 miles of driving), the gage will show full and operate normally.

Cause:
The cluster has built-in diagnostics that cause the gage to blank and flash when an open circuit is detected. The calibration of the set point is close enough to the maximum output of the sender that some senders may cause this condition.

Correction:
This condition may be corrected by adding a resistor in parallel with the sender wire by using the following procedure:

(a) Disconnect negative battery cable.

(b) Remove lower rear seat cushion (retained by two bolts under the front edge of the seat). Pull the insulation mats on the left side out of the way.



Open the conduit on the left side of the vehicle and locate and pull out the pink wire and one of the black wires (Figure 1). Strip about 1/2" of insulation from the pink wire, then solder one end of a 2000 ohm, 1/4 watt resistor to the pink wire. Then strip the black wire, and solder the other end of the resistor to it. Tape the wires and resistor, and place back into the conduit.

The resistor can be obtained from an electronics supply outlet, such as Radio Shack.

NOTICE: THE RESISTOR MUST BE SOLDERED IN PLACE! ANY OTHER TYPE OF CONNECTION WILL NOT CORRECT THE CONDITION PERMANENTLY.

(d) Replace lower rear seat cushion, and connect negative battery cable.

[whitetalonb16g]

crap, I just checked this thread cause I forgot about it, But THANKS ALOT bereta1  and everyone else that helped !

[88*Beretta]

Date: SEPT., 1988
Subject: ELECTRONIC CLUSTER (U52) REPAIR

Model and Year: 1987-88 BERETTA, CORSICA WITH U52 OPTION
TO: ALL CHEVROLET DEALERS

Still have a copy of this?

[Joseph R]

Hello so I have a 90’ Beretta yellow Indy Edition. The left side of the gauge went out. I noticed it flickering then wen out. Anyone know if this can be fixed! Thank you!!

[Rettax3]

Hello so I have a 90’ Beretta yellow Indy Edition. The left side of the gauge went out. I noticed it flickering then wen out. Anyone know if this can be fixed! Thank you!!

Hello and welcome to the site! Yes, most likely your cluster can be fixed by removing it and replacing the bulb(s) along the bottom -these actually back-light the display and the LCD screen of the display 'allows' light to pass through the segments, or blocks it as appropriate. These are not the typical plasma-type display clusters typical of the era, and are actually pretty decent for reliability, and take very little power to run, aside from the bulbs. There were two sizes of bulbs used, the more common T10-base 194-type bulb, and a smaller one that was hard-wired into it's PCB socket, those are harder to find replacements for. Either way, replacing them with LEDs is a good upgrade.

I also have a Digi-dash Yellow Indy (and a Digi-dash Teal Indy, and a Digi-dash white GTU edition, and... ). Pics are very welcome here, hoping to see some of your car. Good luck with your cluster fix...

[Joseph R]

Thank you so much for the help! Now the dash is displaying random numbers. My mileage is way off from what it was. And another thing I noticed is when I use the dimmer. It does not dim but just cut off and on. Seemed like this is goin to be a problem. Anyone experience this before?

[Rettax3]

Here is where it starts getting tricky... The random number display is 'sometimes' (actually often in the past, but as these clusters age, who knows what will become the primary cause of failure?) caused by a poor connection between the actual glass LCD display and the board controlling it. CAREFULLY dismantling the cluster reveals a soft grey rubbery strip which is the actual conductor from the display to the board -gently cleaning it and both contact areas with isopropyl alcohol 'sometimes' restores the cluster to functionality. I have fixed one or two clusters this way (need to fix my Yellow Indy's again -one segment in the speedometer section isn't 100%), but had one that this procedure didn't do any good for too, so proceed at your own risk.

For your dimmer problem, that is much easier. Since your backlights are not controlled nor regulated by the cluster itself, the problem isn't some mysterious VDO voodoo magic. This is usually caused by the interior light dimmer voltage control. It is behind your map-pocket under the left side of the dash.

I know O'Reilly sells them as the 'dimmer switch' (not a switch at all, actually a transistor) part # DS349 runs ~$44 from them -probably half that from Rock Auto. Virtually every GM vehicle from the era used that thing, or the hat-shaped transistor in it, so when I bought my Yellow Indy several years ago, I replaced mine with a junk-yard part and saved the money -they don't fail often.