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Discussion Starter #1
Here is a weird situation and I need help from the LT community.

While having my annual inspection done and my 2005 Elise hooked up to the state computer via OBD2 port my tach dropped to zero and the gauges went blank. The car was running normally but the tach dropped to zero, temp disappeared, fuel showed empty and the low fuel light went on.

Once we unplugged the OBD2 cable the gauges came back to life and them temp came back up to normal. Plugging it back in caused them to die again.

We checked the fuses under the access panel and on the firewall and they were all fine.

My handheld OBD2 reader also can no longer communicate. It worked fine about six weeks ago when I got a CEL on track.

The car runs fine. I have never done anything to the ECU and have no other issues. Ideas?
 

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This is normal on white dash cars...
 

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Discussion Starter #3
Is there a workaround? I've never had issues with this before. I was unable to get my state inspection completed as a result.
 

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The can bus is available at the obdii connector.. presumably to allow flashing/diagnostics of devices like the cluster that are on the can bus.

The scan tool that was used by the state must have flooded the can network with the wrong baud rate or shorted the network or something that stopped normal can dash messages from flowing between the ecu and the dash.

But no worries, no long term harm in it.
 

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Premium Member
2005 Lotus Elise; 2007 Lotus Exige S; 2012 Porsche 991S
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Sorry to revive a super old thread, but I have been having this problem too.

My situation is that I'm trying to run Harrys Lap Timer (Android app) and use my bluetooth ELM327 OBD2 dongle to collect some car information during track days. But while using it, the dash zeroes out at random times around the track, which is a bit disconcerting. (Though the car is still running fine.)

I posted on Harry's Lap Timer forum and he said the issue was my OBD2 dongle, but when talking to a couple of guys at Laguna Seca today they said it was this CAN-BUS issue you guys mentioned.

Someone said I could just yank out the CAN-BUS pin (or pins?) from my ELM 327 OBD2 dongle and I should be OK? Anyone know for sure?

I found this article, which seems to say that CAN-BUS high is on pin 6 and CAN-BUS low is on pin 14.

Should I disable those two pins with a wirecutter or something? BTW my car is a 2005 Elise with the white dash.
 

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I use a GoPoint BT1A with Harry's Lap Timer, and it doesn't interfere with my gauges. I do have a CAN scanner from PLX and another CAN code reader, both of which interfere with the gauges. So, this confirms your CAN interference theory. Clipping those pins should work, but maybe to be less destructive, you can buy an OBD-II extension cable for less than $5 and just clip the pins on that, leaving your code reader intact.
 

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2005 Lotus Elise; 2007 Lotus Exige S; 2012 Porsche 991S
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Are you using Harrys on Android or iPhone just to confirm?

I was thinking about just picking up a GoPoint BT1A, but it seems that maybe they aren't selling them on their site anymore due to an acquisition? The products are listed but there doesn't appear to be a checkout process.
 
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