Something that happens occasionally when I activate the solenoid on the GV unit is the check engine light will flicker on and off for a fraction of a second.

Is the solenoid putting some sort of noise on the 12v line? Or a back EMF or something?

If so what can I do to mitigate that?

 

it would be hard to comment without knowing what your circuit looks like... ie what is the interface between the ECM and this gear vendors circuit

are there any other symptoms at the same time, ie the engine feels like it momentarily misses? if the ECM momentarily would go through a reset the MIL would flicker just as an example

 

The GV solenoid is just run from a switched 12V. Switch is on the shifter handle. Not connected to the ECM. The engine does feel like a momentary miss occurs. It's all like in a fraction of a second. .​​​​​​​

 

Put a fly-back diode across the solenoid. Like what GM did for the A/C compressor clutches.

RBob.

 

Oh interesting. Thats a good suggestion. Thanks RBob.

 

I found that I still had my diode from when I was running the R4 compressor (before I switched over to a Sanden). So I just put that on. I'll drive it around for a while before declaring victory. The glitching only happens occasionally. So ill have to give it enough time to occur again.

 

Although my combination of a GV on a computer controlled car is probably very rare, figured I"d close the loop on this thread...

The diode off the old R4 compressor seemed to help considerably, but I was still getting the occasional ECM hiccup.

After a little more research, I came across this Ligenfelter TVS diode (Transient Voltage Suppression).

https://www.lingenfelter.com/product/L450080000.html

Wired it across the solenoid terminals as instructed and that seems to have done the trick. Not one hiccup since I installed it a few weeks ago.

I left the R4 diode wired as well. I have a bank of relays that converts my momentary switch on the shifter into a toggle, and the R4 diode is on the input side of that relay bank (facing the rest of car's 12V system). The TVS diode is now on the output side of that relay bank. I had though that the R4 diode would shield the electrical system from anything going back upstream off the solenoid, but there must be some other sneak path some place.

The TVS diode is evidently now clamping the voltage at the source.

Not sure the TVS does the trick all by itself or if the R4 is still helping. But any rate, hope this helps someone in the future. I tend to like to close the loop on stuff like this for that reason... I know often times I'm searching around for information on obscure questions/issues.