Technical > Wiring & Sensors

Ground loop problem?

<< < (2/2)

hilly:
Having the GND and GND5 joint at 20cm shouldn,t really cause a problem if you used a decent gauge of wire.

My own personal rule of thumb is to use all wire for grounding at least twice the gauge (more if possible) than anything else, have lots of them and make sure it is a very good connection to the car as poor ground impeadance causes so many problems.
Remember all the currents from the different supplies (injectors, coils, relays, idle valves, lambda heaters etc) ALL return through the grounds of the ECU.

Where is the ground for the RS232 lead connected to ?

Next thing to try is check the GND and GND5 just in case the current ones have failed somehow.

Hilly

dnb:
I've had VEMS in the Griff for nearly 2 years now, without this happening.  So something has changed that I haven't noticed yet.  Maybe a joint has got caught up in something and broken.

Believe me - the engine loom I made for the Griff is over engineered ;)   

It's a shame the rest of it (the stuff I didn't do) is so poor.  So unless I rewire the whole car I am unlikely to suceed at getting a good ground plane that has equal potential to GND5 everywhere in the car.

This adds another reason for wanting to have wireless comms with the ECU - it removes a long wire and gives total immunity from this ground problem.

hilly:
If there is a problem with your grounding (which it appears there may be) then it is at least worth having a quick peek at the loom as it may have suffered a bit of damage which could eventually take out something else................

Hilly

dnb:
Exactly... 

I've just looked at the engine loom & there is no problem.  Also, the datalog from this morning shows minimal noise.  (Laptop on batteries again)  Whatever is causing the problem must be in the body loom - which is virtually inaccessible without taking most of the interior of the car out.

I'll probably find the cigarette lighter wiring that you can't see is the automotive equivilant of bell wire!

cliffb75:
If you expect to use the laptop power supply in the car often I'd suggest installing a power jack with a better connector. We tend to use banana plugs, wired straight from the battery (fused of course ;)).

For continuous use, we find the cigarette lighter plugs tend to overheat and melt the plastic. Plus they have an annoying tendency to work loose through vibration, and you suddenly find your laptop has gone flat when you thought it was charging.......

Navigation

[0] Message Index

[*] Previous page