Just watched your video about resetting ECU. We have 2005 Volvo XC70 which wish I'd never bought but... Just disconnected battery so could change PCV box. Now runs like crap, no response when step on throttle, but no codes showing. Want to reset ECU, but in you video about resetting ECUs, you recommended not to do it on Mercedes, BMWs etc, because of all computers on them. Do Volvo XC70s fall into this category? Or can I reset the ECU by jumping between disconnected + and - battery cables as you show?
If you disconnected the battery, then you already reset it. That's probably why it's running like crap. The computer now has to re-adjust. If you reset it again, it will only prolong the process.
Thanks MountainManJoe. I'm talking about the full ECU reset Scotty talks about in his YouTube video "Doing This Will Reset Your Car and Fix It for Free" where you disconnect both positive and negative cables, and the put a jumper between the pos and neg cables to "drain" any stored up energy in the ECU - letting it sit for 5-10 minutes. He also said he would not do this with Mercedes or BMWs or other fancy cars because they have so much computer controlled stuff in them this will cause more trouble and have to go to mechanic to have codes reset anyway. Our 05 XC70 has a lot of computer controlled stuff in it and want to know if he thinks Volvos are too fancy for this jumper reset to work without causing too much trouble and need for mechanic to reset anyway. I'm used to my '90 F250 7.3 IDI superduty. Heck, even my 03 Trailblazer has way less computer crap in it. I'd use the jumper on the Trailblazer and wouldn't bat an eye, but the Volvo? So much computer crap in it, I don't want to make things worse, but I also don't want to take it to a mechanic, especially a Volvo mechanic, if resetting the ECU really is simple as a jumper between the two cables. I need the $500 they'll change to fill up the tanks on the F250 IDI!
I'm talking about the full ECU reset ...
Yup, I know what you're talking about. (it was discussed in a previous question)
A jumper drains off residual charge almost instantly, but you don't need it. The charge bleeds off by itself in a little while regardless.
And it's actually not a "full reset". There are many parameters that are stored in permanent memory which are not "volatile" (they don't require a power source). Unhooking the battery has no effect those things.
The best way reset things reliably, in a controlled way, and then be able to monitor the results, would be to use a proper diagnostic tool.
Anyway, all you need to do is drive your car. The computer should fully adjusted within a few drive cycles. (again a diagnostic tool would provide readiness monitor results). If it still runs like crap a week later, then you have problems that need actual repair , not reset.