First post here guys, have had my 99 FRC for a few years now.
Developed a strange flicker of the gauges this summer with the lights on- Only the UV lights that illuminate the gauges. I have read and read every possible thread on this subject, and still cant find anything like what my dash is doing. It seemed the longer I drove at night, the gauges would just completely cut out and would not come on, maybe after 5 or 10 minutes...but always started with the flickering before going out totally

- Very Basic FRC- Non Bose, No HUD, Manual HVAC, No Telescoping wheel, No Twilight Sentinel that I can find, no memory seats, Had Tape deck stereo. Not sure if that info will help...

New this summer- Duracell AGM battery, always on Battery Charger/tender/maintainer.

-When you open either door- Gauges light up, but will flicker, and not always the same brightness level, sometimes they are steady lit up for 30 seconds, then start to flicker, very randomly, and just cut off, not always coming back.

-Will flicker with the parking or headlights on- They will change brightness with the dimmer ****, but also cut on/off erratically(more on this...)

-The Switches in the doors and HVAC(manual style hvac) all dim consistently and have Zero issues, also the MPH on the dash dims consistently, DIC read-out works perfectly as well... no cutting out/flickering like the gauges

-I disconnected the Dimmer ****, the Gauges still light up when you open the doors, as well as the rest of the interior lights/door switches, but no dim function as expected- i thought maybe it had something to do with a faulty dim switch,

- I have thoroughly cleaned every ground and ground splice pack on the car- all were clean anyways- this car came from original owner who took very good care, bone stock, no wires cut, etc, and has shown zero signs of water intrusion anywhere. I had the entire interior out when I wired and installed my stereo/amp/speakers, an sound deadening( non-bose car, so I installed head unit, ran speaker wires from the amp to new speakers, very basic/standard install) All the wiring on the car looks in great shape

-Cleaned and inspected the Mult-Function switch- It Looked good, and my parking/tail lamps/turn signals never had an issue, even while the dash gauge lights flicker and completely cut out, so this rules out the MFS I believe.

-Cree LED on outside lights with Hyperflash harness from RadioFlyer- have had this set up for 2 years and never an issue, also led interior lighting from west coast corvettes- again, zero issues with any of those lights or dimming functions. All lighting sockets in very good shape
-Don't think its in either door latch circuit, as I get Door Ajar warnings on DIC, and courtesy lighting works normally

-Am I looking at a faulty IPC or Power Supply for the UV bulbs in the cluster?? Especially since the gauges will light up when you disconnect the Dimmer ****, and open the doors(note- the MPH stayed dark while I did this test, but MPH dims normally when dimmer hooked up).

The flickering, and flat out not lighting up is so random, and seems to get worse the longer power is applied to the gauges...IPC Power Supply??? Its both bulbs flickering/cutting off at the same time, so I believe the bulbs are good.

Have the full 3 volume Factory Service manual and test/metering equipment in my shop.. but having difficulty tracking down where all the IPC/Power supply for those UV bulbs gets its power from...

Was wanting to swap In a Z06 cluster soon anyways...but now I wondering if I have issues elsewhere

Thanks guys??

 

Did some testing, ran some numbers at the short harness from the IPC board to the High Voltage Supply for the UV lights
Key Off:
Red- 7.5
Green- .12
Blue- .12
Yellow- 12.4
Black- 12.4

Lights on Dim Low Dim High
Red 7.6 2.2
Green .023 .086
Blue .023 .09
Yellow 12.4 11.9
Black 12.4 11.9

I then probed a white wire coming out of the High Voltage Supply to see what it was doing, especially when the lights would begin to flicker, switched tester to Volts AC
- Immediately after opening door
- Ranged from 2.3- 157

Then Key On, Lights On
Dim half way--Constant Vary from 80-97, lights flickering
Dim All Way Up- 150- 165, lights flicker some, sometimes steady, but always return to flickering
Dimmed all the way down- would drop under 1

I also inspected the ICP board and the High Voltage Supply Board- Did not see any signs of heat or damage, but I guess that doesn't mean a component isn't on its way out..Do not and have not ever had electrical problems with this car previously

Had battery on the Maintainer, was reading 75%, and when I probed various fuses under hood and in footwell, was well over 12 volts everywhere.. Car had been on charger for 2 months, and started/ran for 30 mins yesterday when moving from garage to house..So battery isn't the issue, as battery is new Duracell AGM

I'm guessing that the High Voltage Supply is taking a crap??? Dimmer works just fine on all other courtesy/door switch, DIC, DIC LCD readout, etc. No DIC codes present in any modes.

Just hoping that I don't have the issue after swapping in a Z06 cluster, as I had planned to do this winter.

 

Since this car does not have twilight sentinel, but it does have the little glass lense above the DIC buttons, could that ambient sensor be playing havoc with the gauge lights?? I thought it was for the LCD dispay in the cluster and the MPH display... those 2 displays have zero issues/flickering, and they dim very smoothly...

 

It definitely sounds like the high voltage supply is on its way out.

 

I'm hoping its just the high voltage supply, and not an issue with the IPC- I'd like to swap my ICP for correct mileage. I guess I'll find out when I hook up a new instrument cluster with my IPC/ New high voltage supply from new cluster...

 

What was the result when you hooked up the new instrument cluster? Was the problem the high voltage supply or the IPC? I'm having a similar issue with my 2000 C5.