Dash Lights 84 C20

[Penguin]

HI,

Stuck trying to get dash lights to work on 84 C20.  Half of them work so suspect it may be the circuit board.  Swapped sockets of working ones to show that it not bulb or socket.  Trying another way (using LED lights but stuck again because there is no cigarette lighter installed which is what these light use.  So tried after market cig lighter that goes directly to the battery but stuck again because I do not see a way through the firewall without drilling.  Any ideas on how I can get the panel lit up?  My teenage daughter is driving it and wants to know how fast she is going.


Thanks

[VileZambonie]

The first thing you need to remember is a an LED is a light emitting diode. A diode allows current to flow in one direction unless otherwise engineered to be bipolar. Simply turn the bulbs that aren't working around and see if they illuminate before you pull your hair out.

[Rapid Roy]

Welcome.

[bd]

...Trying another way (using LED lights but stuck again because there is no cigarette lighter installed which is what these light use....

    Don't get carried away with universal addons.


Be patient while performing the following procedure, allow yourself several hours the first time through, and use an empty egg carton or compartmentalized plastic box to hold all of the screws and keep them organized for easier reassembly. 

Remove the headlamp switch knob (see Diagnosing dash instrument lights for details on how to do this, if necessary).  If the truck has an automatic transmission, rotate the gear selector into low and out of the way for the following steps.  Remove the instrument panel bezel, disconnect the speedometer cable from the back of the cluster and unplug the instrument panel (I/P) harness from the back of the cluster.  If the truck has an automatic transmission, remove the small sheet metal panel directly below the steering column and disconnect the automatic transmission gear indicator cable from the upper right side of the column.  Remove the cluster retaining screws and tilt the cluster out of the dash by rotating the top of the cluster toward you slightly while lifting upward.

Once the cluster is out, if the circuit board is compromised, such as a broken or peeled copper circuit foil, a careful visual inspection will discover it.  As long as there are no visible breaks in the copper foil, carefully burnish all of the dash bulb socket connection points and the I/P harness connection points (both the connector terminal faces and the foil) using a soft pencil eraser or crocus cloth.  Be careful while burnishing that you don't peel the foil away from the plastic substrate.  Check the tension between the bulb sockets and the cluster housing and gently bend the socket contact arms to increase tension if necessary.  Replace all of the bulbs (168/194) or upgrade to super bright LEDs while you have it apart.  Likewise, check the tension between the I/P harness connector terminals and the cluster socket.  Plug the harness back into the cluster and verify that all of the bulbs illuminate before reassembling in the reverse order of disassembly. 

As VileZambonie mentioned, if you upgraded to LEDs and some of the bulbs don't illuminate, remove the bulbs that don't work, rotate them 180° and reinsert them, then retest.

[Penguin]

Hi BD,

So I completely agree with your long term solution, but we are in rainy season up here followed by snow and I do not have a garage big enough to put this truck in.  Also it is a daily driver for my daughter and I know how these dash removal projects can drag on.  Bottom line is I am looking for short term fix so that she has lights on the dash.  I bought a set of LEDs that connect to a cigarette lighter and also a after market light that connects to the battery, this would work if I could string through the bulk head.  Any ideas how to do that?  OR do you think I should try burnishing the contacts on the back of the dash without pulling the dash.  I will do a rebuild, just hoping I don't have to do it in the rain.  Thanks again

[bd]

Don't try to burnish the PCB with the cluster installed in the dash or you'll risk introducing more problems than you had before you started.  Connect the center terminal of the cigar lighter socket to a fuse box cavity marked "BAT" and ground the socket shell.

I think that after it is all done and over you will find that repairing the existing cluster properly isn't much more difficult (or wetter) than adding the universal lights.  Best of luck.

[VileZambonie]

If it's your daughter's daily driver, do it right. The amount of work required to remove the bezel and gain access to the cluster is all of about 5 minutes worth of time and requires minimal tools.