DIY Cruise Control on 07-08 Yaris (step by step)

[yaris07hb]

I created a test box to confirm that this mod works on my '07 Hatch with MT before committing to drilling holes in my dash. The box is a portable version of the mod, containing two momentary switches and the correct resistor value. Yesterday, I poked out the rubber seal from Pin 40, ran my ground, and went for a putt. Nothing happened - except that the car began idling really slow - rattling and such. The A/C kicked it back into a normal idle. So, reading further I discovered my mistake - the clutch switch. Today I jumped the correct terminals, reattached my test box, and went for another putt. The cruise function does indeed work correctly (thanks to you smart folks). However, I still have a very low, very rough idle. This was not the case before yesterday.

Is it possible that my failure to follow instructions, not jumping the clutch switch terminals, and attempting to activate the cruise has affected my ECM? I find nothing out of place, nor did I disturb anything other than the ground lug on the battery and the ECM connector to install the wire at Pin 40.

Has anyone else had a rough idle during or after performing this mod? Is it a super-coincidence that I now must perform a forum search on rough idle, and then go clean my MAS or something else?

Thanks...

[CTScott]

Originally Posted by yaris07hb

Is it possible that my failure to follow instructions, not jumping the clutch switch terminals, and attempting to activate the cruise has affected my ECM? I find nothing out of place, nor did I disturb anything other than the ground lug on the battery and the ECM connector to install the wire at Pin 40.

Has anyone else had a rough idle during or after performing this mod? Is it a super-coincidence that I now must perform a forum search on rough idle, and then go clean my MAS or something else?

Thanks...

Forgetting the clutch switch or bypass of it wouldn't cause an issue, other than the cruise not kicking on.

Your rough idle is probably due to having pulled the connector off of the ECM. Connector A21 carries power to the ECM, so when you pull it, you reset the short term data. Drive it for a couple of days and it should cure itself.

[WolfWings]

Originally Posted by yaris07hb

I still have a very low, very rough idle. This was not the case before yesterday.

Same thing happened here when I first did the mod to install the factory stalk on my '07 MT LB, CTScott's right: Give it a full tank of gas to re-learn things, it'll behave itself again.