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Bypass Test Rant

  • Tutti57
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08 Mar 2020 11:40 #38144 by Tutti57
Bypass Test Rant was created by Tutti57
Maybe the title should be different, but, a guy just put a junkyard engine in a 2008 or so g37. He got it running but then it was dying out with a crank sensor code, I believe p0335. He isn't very comfy with this type of stuff and was using the flow chart which wanted him to do the standard ohm tests at ECM, which is up behind the glove box. I told him if there is a pid available, he could do the bypass test to confirm circuit integrity on the signal wire. It's a 5v pull down design.

Next day the guy next to him comes over to tell me that my test would short out the ECM and that I shouldn't be telling people stuff like that. I tried to explain it but it went over his head and he said maybe on the old old styles but not on these new closed circuit ecms, whatever that means. How there isn't a fuse there and touching battery ground was not an legit or approved test.

Obviously this was super annoying and got me fired up for a while. Pretty much anytime this guy sees me helping someone he comes over to undermine me. It's gotten to the point where I just walk away when he shows up.

He saw me doing an evap smoke test recently and asked me why I was pumping smoke into the engine and not the evap system. I explained that the purge valve is closed and that it wasn't going into the engine. He said that it is open and that I am not used to Nissans. I was about to pull the valve off to blow through it for him but I just got frustrated.

Another time he saw me using my uscope and told me it wouldn't work on Nissan's because he has 6 scopes and none of the scales align with how the manual recommends you set them up.

It's super frustrating. He is seen as a go to guy for questions and it's hard to tell if he really doesn't know, which is what I think, or if he intentionally leads people in the wrong direction.

He is super fast doing transmissions and big jobs, which is why I think people assume he knows this other stuff, but cripes I don't know how to deal with this.

Nissan Technician
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08 Mar 2020 12:31 - 08 Mar 2020 12:37 #38145 by Noah
Replied by Noah on topic Bypass Test Rant
Just ignore him and fix cars. Eventually everyone will see that you're solving the problems 99% of the time without comebacks. When people stop asking him for help and start asking you maybe he'll realize that you do know what you're doing after all.
I went through something similar when I transitioned from the junk yard to the shop.
When contracdicted by the "lead tech" I would just say, "well that's what I would do, but try it his way first."
Eventually no body wanted to try it the "right way" first, lol.

"The circuits in cars are not nanby-pamby Chinese consumer electronics "
Last edit: 08 Mar 2020 12:37 by Noah.
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08 Mar 2020 15:27 - 08 Mar 2020 15:29 #38149 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic Bypass Test Rant
As you well realise and he dosen't sensor inputs on engine computers are well protected and practically impossible to damage by grounding --- my guess is at some point in the past he has burned out a computer driver output.

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



Last edit: 08 Mar 2020 15:29 by Andy.MacFadyen.

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08 Mar 2020 15:46 #38150 by Tutti57
Replied by Tutti57 on topic Bypass Test Rant
Is that because they have an internal resister on that circuit?

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08 Mar 2020 16:56 #38154 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic Bypass Test Rant

Tutti57 wrote: Is that because they have an internal resister on that circuit?

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Basically yes the ecu measures the voltage before or after a resistor .
Inputs can only be pull up, pull down or a voltage none of which get hurt by grounding.

Pull up tends to be found on things like the instrument cluser air bag warning lights where it really works the same way as the charge warning light and the voltage takes away the ground for the warning light

Pull down is now more common works works really much the same way as pull up

Voltage devider the classic examples being a temperture sensor

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(Walter Bishop Fringe TV show)



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08 Mar 2020 17:49 #38158 by Tyler
Replied by Tyler on topic Bypass Test Rant
I know exactly the kind of tech you're describing. :angry: You can chalk his attitude up to all kinds of stuff. Industry mythinformation, anecdotal evidence, whatever. It doesn't really matter. Like Noah said, just fix cars. Your results will speak for themselves.

I've received that kind of pushback at almost every shop I've ever worked at. It ALWAYS ends with the tough cars coming to me. :silly: As long as you're OK with getting the tough jobs, keep doing what you're doing.

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26 Mar 2020 08:52 - 26 Mar 2020 09:02 #38654 by Dtech494
Replied by Dtech494 on topic Bypass Test Rant
Hi its a 4-5 volt pull down signal. You could look at the pid and tap signal low with test light to ground. Or if you turn the engine with a ratchet you should get either hi or low (o or 5v) if checking pid an depending on the crank position.
Not having tested the vehicle but looking at the info.
The voltage will be regulated to 5v with the circuits and it may even go
to directly to a processor pin so there is likely not enough current being supplied that it could harm itself. IMHO
As Andy mentioned yes there will be resistors ahead of the circuit.
Last edit: 26 Mar 2020 09:02 by Dtech494.

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