Relays

[pfarmer]

08 G35 Sedan XS - There are two relays under the hood, one by itself marked something like ACC brake relay, the other in the battery compartment marked something like Shift Lock. What do these two relays do?

The reason why I ask is that I have been having this on again/off again start problem. Typically it has been you push the brake down, push the button, and while the rest of the dash does what you would normally expect the car does not turn over. I have taken it in to the dealer and of course while it shows various codes related to the starter (relay, button, etc) it refuses to show itself for the dealer.

Today it acted differently. On one occasion nothing happened until I released the brake and then the engine started. On another I released the button and then the engine started. In between the engine starts to crank and then stops, some times chattering like a weak battery (car has about 11 k miles.)

Since I ran into problems on another car of mine and I swapped two identical relays on it and the problem went away (transmission related) I decided to do the same here. Both these relays are marked identically so I figured what is there to lose. While I only have a few starts since I swapped, the starts have all been normal.

Can either one (or both) of these affect the starting of the car?

Perry

[kmckis1029]

(just talking from a straight electrical stand point and general knowledge of how a push button start works)

when you press the start button, the car's computer checks that alot of sensors/relays are in a certain state, then once that is comfirmed it will start the car. (thats the simple version)

So if that ACC brake realy and/or shift lock relay are in the car computers "list" of things to check before starting and its malfutioning, the car wont start.

now you said you switched two relays and everything seems fine... you might of solved your own problem

[pippen99]

He didn't solve the problem. He just transferred it to a different system. Personally I would rather have a problem with starting the car to diagnose than a problem with the brake system that rears it's ugly head while trying to whoa down a two ton car from 60 mph!

[pfarmer]

He didn't solve the problem. He just transferred it to a different system. Personally I would rather have a problem with starting the car to diagnose than a problem with the brake system that rears it's ugly head while trying to whoa down a two ton car from 60 mph!

Actually I don't think I did either. First off I doubt that the relay marked ACC brake would be the cause of me not being able to stop the car. Still not sure what it actually is but since I have the laser type cruise control I am thinking it may be associated with it.

This morning it did its thing again. Now after doing this I started paying particular attention to exactly where I pressed the button. So today I pressed it at about the 8 o'clock position and it started each time at that position. Probably not it yet but I need to be able to figure this out on a consistant failure basis or hopefully it just fails completely.

If this is it then I'll press Infiniti to replace the switch even if they can't duplicate it. If not then I'll press them to start doing more than looking at codes which up until now I think that is all they really looked at.

Perry