Input terminal problems

gizmodo · Post by **gizmodo** » Mon Nov 04, 2013 2:09 pm

It seems as though each input isn't correctly isolated from the others. I had the same problem as this post: http://autosportlabs.org/viewtopic.php? ... ght=#19825

This past weekend I was playing around with the RCP and noticed something even more problematic. I have my throttle position sensor hooked up to analog 1, and my brake input hooked as a digital input. When I press the brakes my engine revs up about 250 rpm and stays there until I let off the brake. I had just done a lot of work on the car so I spent a few hours going over all the vacuum lines and came up with nothing. Then I pulled the fuse for the brake lamps and the problem went away. So I spent a few more hours looking over all the electrical and found nothing. Then I remembered the RCP was hooked to both things. Sure enough, if I remove the brake or the throttle input the problem goes away.

I tried all combinations of analog inputs and digital inputs and I could not have them both hooked up at the same time.

andylaurence · Post by **andylaurence** » Mon Nov 04, 2013 4:35 pm

That's scary stuff! Lucky you didn't find out on the track. Nothing worse than the throttle picking up under braking. I had it happen this year (the ECU controls secondary throttle bodies based on TPS input) and nearly had a bump. I'd like to blame my crash at Crystal Palace on it, but that was my fat feet hitting both pedals!

I'd suggest a recommendation on the sensors page to avoid tapping sensors connected to the ECU until someone understands the extent of this problem. I'll certainly be sticking to dedicated sensors - inaccurate logging is one thing, but a car you can't control is lethal.

gizmodo · Post by **gizmodo** » Thu Nov 07, 2013 1:47 pm

Any thoughts on this? Should I sent it in so you can take a look?

gizmodo · Post by **gizmodo** » Tue Nov 12, 2013 7:58 pm

Is there anything I can do about this? As a datalogger the RCP is becoming less useful to me since I can't log what I want anymore.

Post by **brentp** » Tue Nov 12, 2013 10:51 pm

Thank you for reporting this. Can you tell us more about the voltages going in to the brake input circuit?

what voltage do you measure at the terminal when you have the brakes on vs when they are off?

We'll be sure to get to the bottom of this.

-Brent

Post by **brentp** » Tue Nov 12, 2013 10:59 pm

Another thing you can do after you measure the voltage input:

Test driving the brake input with 0v or 5v:

1. Disconnect the connection to the input coming from the brake line.

2. Connect a short wire from the terminal block and bridge it to ground. Note the value being logged and any change in throttle behavior (like you saw). Confirm 0v on the digital input.

3. Now connect the wire to the 5V voltage reference on the RaceCapture/Pro terminal block. Note again the logged value and any change in throttle behavior. Confirm ~5v on the digital input.

Let us know what you find out.

Thanks,