What is the correct wiring for a pair of Spartan 3 Lite V2’s?
Currently I have both white heater grounds ran directly to the battery negative, both red power wires running to battery positive, and each black electronics grounds ran to a single chassis ground where the interfacing device is grounded. It seems to work fine 90% of the time but once in a while, the output from the controller ends up being total garbage. Instead of both reading around 2.2-2.3 volts, one will read anywhere from 5.0-6.0 volts and the other will read anywhere from 0.7-0.8 volts. Is this because I have each of the electronics grounds at the same chassis ground location?
Both Black wires should be grounded to where the device connected to the green wire is grounded, ECU, gauge, datalogger etc… Both white wires should be grounded to chassis. Red wire I recommend tapping power from the fuel pump relay.
Ok I’ve made some changes. I’m obviously doing something wrong here. I’m using an SCT X4 with a FireWire cable to log these in livelink. The green wires are connected to the analog inputs of the FireWire. Both black wires are connected to the respective analog ground wires of the FireWire. White wires and red wires are still hooked up to the battery for testing only since this isn’t really working.
Problem now is they are putting out 5V right away with no warm up sequence. What is going on here?
Disconnected green wires. Measured with a multimeter. Still 5 volts immediately. No warm up cycle. Went back to the original wiring from the first post. Warm up sequence works fine.
With the the original wiring from the first post though, I still end up getting a weird reading every so often of near zero volts from one wideband. And 5-6 volts from the other. Could this be caused by the single chassis ground tying all the black electronics wires and the analog ground wires to a single point? What would be the best remedy for this? Thanks
The inconsistent voltage readings you’re experiencing between the two Spartan 3 Lite V2 devices could be due to several factors. One possibility is indeed related to the shared ground location for both devices.
Power:
Positive: Connect the red power wires of both Spartan 3 Lite V2 devices to a common 12V source (e.g., battery positive).
Negative: Connect the black electronics ground wires of each Spartan 3 Lite V2 device to a separate chassis ground point. This ensures that each device has its own reference ground potential, reducing the likelihood of interference or noise.
Heater Ground:
Connect the white heater ground wires of both devices to a common ground point, typically the battery negative.