Instrument Cluster Problem

Posting here as well as in the GT3 forum, hoping for some direction/help Car in Question - 2000 MY 996.1 CS K400. The problem - went for a drive and suddenly the cluster started to play up. Tacho and Speedo started jumping up and down, while the LCD displays went dead, while still being illuminated. The rest of the gauges - voltmeter, coolant temp, oil pressure and fuel level are working normally. Every now and then, the dash would come back to life for a second or two and then go back to being half dead. Turning the car off and back on does nothing. The tacho needle sometimes jumps up about 1500rpm and then drops down to zero. The speedo needle would do the same while driving. Actions taken: Disconnected the battery. Touched the + and - leads to discharge all systems. No effect. Disconnected the three leads on the back of the cluster. No effect. Will be replacing the alternator - the regulator has been playing up a little bit, while still charging, but I don't think that was the problem. Annoyingly, my internet search threw out somebody with the same symptoms, but there was never a resolution to the problem as the thread went dead. Any ideas? Thanks in advance, Alex

I think the rev counter works via canbus and so it maybe one of the connectors that’s come a little lose. I had clock issue and on investigation one of the connection in the back of the clocks was broken by a previous strip down and had come unseated. Mite be worth check. It’s only 2 bolts to so not difficult to remove

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I tried the connectors at the back. No joy. I also sent the unit to ACTronics - contrary to the testimonials on their website, they were as useful as a chocolate fire guard… P.S. 996.1 GT3s don’t use canbus - it’s all K-line - as primitive as it gets. Think BMW E36 level diagnostics. Porsche were really scraping the bottom of the barrel when they introduced the Boxster/996. Quality is atrocious…

For what it is worth when I popped a replacement engine in my 996.2 the instrument cluster would not work, probably because it had stood idle for the bst part of 2.5 years. To sort it out i connected my foxwell nt530 with the porsche sw pack and there is a section on testing the instrument cluster. I cannot remember what I did othere than press the button and all the gauges and lights started popping and flashing with the pointers on the gauges whizzing up and down. When it stopped everything worked. Did you try this? Another time as I drove my 997 home the alternator failed. I knew of the problem because the battery would not charge. About a mile from home every light on the dashboard came on and there was jsut enough charge left to coast onto my driveway. It looked expensive!!! However £12 or so on ebay and i bought a new regulator pack. It was less than an hour or so to strip,clean and fit the new regulator and all was back to normal. I wrote a post with pictures on here to show how easy it is to do. So I was wondering if you might have a combination of problems. BTW what did ACtronics discover?

I think you are right. It’s a multitude of factors. While I sent the clocks away to be repaired I also changed the alternator to a brand new Bosch one - new old stock - which I picked up for £175. It would have been a shame not to at that price. Fitted a new battery. Awaiting on the return of the dash from ACTronics… What they discovered - I don’t know is the honest answer. I was told they changed the LCD panels, which was totally unnecessary, since they were always correctly illuminated and would flicker back to full life every now and then, and they could not get the analogue gauges to work anway. They lost me when they said that their most experience engineer could not get the gauges to work - they are analogue. They respond to simple electrical inputs - it's a stepper motor, not the Saturn rocket. Hoping to get the clocks back today/tomorrow. Will plug in and if still no joy - will send off to Autotronics. A member on here had a result with a tacho on a 996 which showed silly numbers. So I get the feeling that Autotronics at least know what to look for...