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Discussion Starter · #1 ·
Just had the car into the shop to get a new clutch, 3.73's and WB o2 bung welded in. Had the PLX WB sitting waiting to be installed, THANKS JOE, and finally got it wired up this past weekend.

I used an "add a circuit" from the autoparts store to tap into fuse 20 I think which is for the convertable top. I figured this would be a good one since I have a hard top and it is key switched.

Well on my way into work today my speedo would randomly jump to zero then back to the right speed or in the hundreds and back down. :eek: Then a random "service engine soon" light followed by other random lights on the dash. The car seemed to be running good but my 55 mile commute coupled with this had me concerned. I ran through what I did and decided to unplug my SCT livewire (the plx is wired into it). No change. I then reached down and unpluged the power from the PLX control box(which kills power to the WB o2). This solved the problem. All the intermittent issues with the gauge cluster went away.

I assume I was drawing too much from that circuit or introducing a ground loop of sorts. It was a 20amp circuit. I put the 20amp back in the add a circuit with my new 10amp fuse for the PLX. Should be a harmless combination.

During lunch I jumped under the dash and moved the add a circuit to the "intermitent dimmer lights" circuit. I'll see how it does on the way home.

Has anyone seen this while tapping into their fuse panel?

I have the PLX control unit grounded to the battery through a dedicated cable I ran just for this purpose.

If anyone else has the livewire let me know what success they had with analog input1. I had a raw value of 2.5-5volts at the end of the cable that plugs into the LW but read 7+ volts as raw from the device no matter what I did. Re did the wiring this time using Analog2 and the readings are spot on. Not sure if my unit is faulty. There is little to no documentation on the external hookups available.

JOE: Do I need to put those micro capacitors in the cable you supplied? They were in my PLX kit but not wired into the cable you supplied.

thanks
 

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Discussion Starter · #2 ·
After switching to a different fuse with the add a circuit the frequency of the issue dramatically reduced. I only noticed one instance of a gauge sweep on my 1 hour commute. additional testing last night resulted in finding out if I disconnected the livewire while it was in data monitoring mode resulted in an immediate gauge sweep of all the gauges. this leads me to think there may be a ground problem though I find it hard to believe since I ran a dedicated ground to the battery.

perhaps I should choose a chasis ground closer to the fuse panel to bring the two references closer? I thought by chance the cat5 connector into the livewire was loose and as I was driving it was disconnecting but I tugged on it like a school child on a leash to a dog with no results. Besides, when that connector breaks contact all the gauges sweep instead of the 1 or two that I was noticing on my drive.

anyone have any thoughts with this?
 

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I have not seen this before. I would suspect the livewire has an issue. Maybe something caused by using the analog 1 circuit. A gauge sweep is normally due to a battery disconnect. The livewire might be sending bunk data up the obdii port. Try running without the LW plugged into the obdii port with the plx on. I never use the capacitors. Call up SCT and let them know the issues you are having.
 
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