Just a quick question for verification. I have done resets both by touch neg wire to positive terminal or leaving battery disconnected for an hour or so.

Someone who has experience with older cars- pre -ODBII -suggested that disconnection of the battery and stepping on the brake pedal would have the same affect as touching neg to. positive.

Do these newer cars operate that way and has anyone done such successfully for a hard reset or does it have no effect?

Thanks

Tom in Plano/Dallas
05 S -type 3.0 103,000

 

I have done it both ways, disconnecting the negative and positive terminals and touching them together, also leaving it disconnected for 30 minutes or more.


There have been times where it has worked, and other times no. It will depend on what the issue is.


The hard reset is part of the diagnostic process, but doesn't always fix the problem.


What is the issue that you're having?

 

I do not have an issue at all (except that I want a new XJ) I was just - for the sake of a discussion with someone else- wanting to know if stepping on the brake pedal after disconnecting the neg terminal would effectuate a hard reset and capacitor drain on the ODBII cars. I think that was something that worked from the 70's-80's, but was curious if it still had or had any impact at all for a hard reset.

Tom

 

It would be more work to get inside the car to press the brake pedal than the conventional method of touching the two leads together.

Most so called hard resets either do nothing or are not required anyway.

 

That I understand.
I am just trying to ask if the brake pedal push method will do the same thing for draining the capacitors. If the car is running fine, there is no need for resets as the probably would make less than a 3% adjustment to be back where you were before the reset unless you were adding something like a maf or 02.

Thia is just a discussion I am having with someone that is old school and stuck in the 1980's and 70's.


Tom

 

Most cars of that era didn't have enough electronics that a reset would have any effect.

 

With all respect, I understand that and agree about the older cars. My question and if someone does not know the answer, join my crowd as I am not sure either, is very basic. If you disconnect the neg terminal from the battery and step on the brake pedal with the KOEO will it drain the capacitors in the same way that touch neg to post. terminal will do or just leaving it disconnected for a certain amount of time?

Tom

 

I'm not trying to be a jerk here, but we actually don't completely know 100% of what happens when we do a reset on modern cars (beyond the basic principals), so knowing what might happen by hitting the brake pedal would also be an unknown.

I've never heard of the brake pedal method until you started the topic.

 

It could only be an equivalent if every circuit that would be affected by the usually hard reset is connected to the brake pedal switches and there are no diodes.

Just go through every page of the Electrical Guide for each of the models and check.

What a huge waste of time that would be!!

So, a simple question with a simple answer that's very hard work and pointless.

 

Thanks- old wives tale I suspect and that fits well for the person that is telling me those things.

T

 

Thanks!! I think you are on point and that is my thought initially as well.

I think the person's reference was that it would drain power from the car quickly, but it does not give the capacitors a path to ground. I suspect it may very well have worked on some 1970 or 1980 car, but I care not about those for myself. I frankly thing it does nothing in more modern cars.


TBB