SPIKEs malfunctioning in "Reverse"

[smcmahon]

We have a pair of Spike relays on our robot, driving a pair of Window motors. Both of them are exhibiting some rather odd behavior.

When we energize them to FORWARD (via code), the lights come on Green (both side car and Spike) and the motors work just fine. Output with a multimeter is measured at 12V (or is it is -12V...) Anyways, the motors spin and everything is fine.

However, when we energize them with REVERSE (via code), weird things happen. We do get Red lights at the correct places (side car and Spike) but they blink very very quickly, almost pulsing. The Spikes emit a very clear, and very fast, clicking sound. The one the left measures around 10.8V and the one on the right measures the proper 12V, but it dips erratically every few seconds or so down to like 5V.

Even more strange, the left one was measuring 4.8V with a mutlimeter in Reverse before that. We then changed both the Spike and the PWM cable to get to where we are now.

We've tried swapping PWM cables, changing RELAY Ports on the Side Car, swapping out the entire Side Car itself, changing the crimp-on wiring connectors. Just about everything. We even checked the fuses on the Power Distribution board. We also double-checked that our Relays were set to "both directions" in LabVIEW.

Again, the really odd part is it only does this in Reverse (red lights). It seems to work fine in Forward (green lights).

Thoughts? Suggestions? Anything else we can swap or check? Anyone ever see this before?

As always, thanks for your time and assistance.