Switching OBD2 wires

Does anyone know if using a relay to switch 3 wires on an OBD2 harness will effect the signal?

I have an idatalink maestro for my headunit and just got remote start installed. The remote start module is making my headunit stay on no matter what unless i have the OBD2 connector disconnected. Talked with the shop that installed it and they called idatalink and viper. Both companies blamed eachother, idatalink offered to write custom software for my vehicle but i would have to pay for it.

 

Draw a schematic of what you have since both vendors are blaming the other

As vague as your question is the only answer is maybe .

The more connections in a given circuit the more place for one to fail

Since it seems what you have does not play well together .

Do you have all the correct parts ?? Are you trying to mix and match things that are not normally used together ??

Without seeing just what you have I think the simple thing would be to install your relay to break the ground to the head unit relay opens it shuts off.

The other option is pay for the custom software and hope it does not crash .

Learn to write code and make your own patch

 

I have all the correct parts and the shop i had the work done at has done similar installs with no issue but not the exact same parts.

It seems to be the remote start module communicating with the vehicle system somehow turns on the head unit. Which is strange since there is no power to the power circuit for the radio with the ignition off.

I have a kenwood ddx374bt deck with idatalink maestro rr and a viper ds4857 remote start.

The ground wire for obd2 is not in the harness for the maestro unit. It is 3 wires and i have found different pinouts for my truck so im not 100% sure which ones they are. The ground was one of the few conistant pins i saw in different examples.

Essentially my idea is to connect a relay to an ignition switched circuit to diconnect 1-3 wires to stop the HU from turning on.

I would only be cutting the harness for the maestro connection, not sure if the wires are shielded or not and how sensitive the signal is. Been trying to source another harness in case something goes wrong but cant seem to without buying a whole harness set.

As for coding my own software, i have been down that road for other projects and i would rather just leave it unplugged lol.

 

Use your relay to open the ground wire for the head unit .

Then no matter what it will turn off

Sounds to me someone has something wired wrong

Without the schematic it is all just a guess.

Best of luck !!