Do you also replace the green signal wire when replacing a CKP?

See Schroedinger's  Box    YouTube:   '  repair of Chevy w intermittent  P  300, p335, p 336'

Question :Do  mechanics   customarily  replace  the   green  signal  wire  when they  install a   new  crank position  sensor?  


Schrödinger    discusses   fix  of   an intermittent  CKP  code P300  random cylinder  misfire .        chevy   had  just   gotten a   new  crank position  sensor  to  fix its   P 300   random   cylinder  misfire.       Car  was  still  misfiring,  especially  at  higher   speeds  when the  engine  was  hot.    

he    fixed P300 s   by    replacing the  green  signal  reference  wire  to the  CKP.      (NOT  the  ground  wire  or  the  yellow  wire.  )               

 
HOW:
he started a  back probe of the GREEN  CKP   signal  wire.        (which was  not  replaced  when the  new  CKP  was   installed.  )     
he found  the old  green  signal  wire to the  CKP  " occasionally  coming loose. "     interrupting   the  signal.   

Rx  was  to  replace  that  CKP  green  signal   wire  w    brand   new.       he  also   checked  the other 2   CKP  wires  (yellow etc  and  they  were  good. ) 


he  suggests to  diagnose   this  problem w  the  wire   use  a    lite or  a  scope  running  2  channels "as the  VOM  won't   fit.       "

All   advice    welcome.        how   many  hours,  and     how   hard  is  it to  replace  the CKP  green  signal  wire ?
 

Replacing wires is not very common, and should only be done when it has been proven that a wire is bad.

Share the video link please. I like Matt, haven't seen that one.

07 chevy express 3500 w/ 6.0 L engine has had repeated p0300s for almost 3 years now. 2 new gas caps, 3 different new CKPs w re learn installed, 1 CPS, canister checked and OK, new fuel tank sending unit. still giving P0300 s at highway speeds when engine is hot. P0300 usually occurs 1/ within 5" after a fuel tank fill up , when engine is hot, from running at highway speeds, or 2/ when I step on the gas to increase speed to pass a truck , etc. while already going 60 + mph.

Noah, my original post contained the you tube video link and the times on the you tube video where Schrödinger's Box talked about each step of the diagnosis. when my post displayed on this on this message board, the hyperlink had been removed, don't know why.

I'll watch it, been too busy for You Tube.
Can you reproduce the missfire by brake torquing the engine?
Do you have access to scan data? Some times a p0300 isn't as "random" as the code description would imply. If you can narrow it down to one bank, or even better one cylinder it would be a big step forward.

I had 2 different mechanics replace a CKP (at a cost of over $300) as the 1st 'fix' to for a p0300 . (The 3rd shop did measurements and did find an unusual drop in signal voltage, and did NOT replace the CKP. ) it seems to me that diagnosing erratic signal voltage , and replacing the signal wire should be a recommended fix. why not check the integrity of the wiring to the ECM carrying the signals for CKP and CPS before a mechanic charges $300 for installing a new CKP ?

according to the freeze frame data, the p0300 occurs in closed loop , all variable look normal except for ST/LT fuel trims which occasionally look a little high. the p0300 happens only at highway speeds in excess of 60 mph, like when I'm passing a truck. ScanTools don't show clues of which injector. no specific P30x codes ever show. Schroedinger's check of the integrity of the CKP wiring makes a lot of sense. 2 years of recording freeze frame data is getting pretty boring.

So have you checked the integrity of the signal wire on the CKP like Matt did in the video you referenced? (Edit: It is worth noting that he was diagnosing an issue that presented along side a code specifically in reference to the crankshaft sensor signal circuit, not a p0300).

why not check the integrity of the wiring to the ECM carrying the signals for CKP and CPS before a mechanic charges $300 for installing a new CKP ?

Maybe they did and found no problem? Or maybe they felt they had enough evidence to move on with repair? I don't like to take shots at other techs who don't have the chance to defend themselves, but if you think the signal wire integrity is compromised get under there and check it out. You can do it!

thanks, Noah . my question was whether the mechanic's time and cost to check the signal wire voltage should customarily be done before a mechanic throwing a 3rd new new CKP in, costing me $300 plus in mechanic time. (especially when 3 new CKP s have failed to cure the P0300. )

To that point I would say, how do you know they did not check the circuit integrity? If you know what is wrong with the truck, then fix it.
Please let us know if the p0300 comes back when you're done replacing the signal wire.

if there is a loose or corroded signal wire, it may not show up until the wire is hot and there is a heavy load on the engine at highway speed. it's an intermittent random p0300, not a constant one. the van is usually left in a parking lot at a mechanic 's or the chevy dealer for some time til they can get to it. then, to diagnose the p0300, they take it for a short road test , but no p0300 misfire shows up. Schroedinger's test method was to test the signal wire integrity from the CKP in his shop , not rely on a road test to diagnose the p0300.

Noah, I am puzzled with your reply to my posts.
1/ did you read this entire thread from the 1st post I made suggesting that the integrity of the crank position signal wire may be at fault in causing the p0300? note that previous mechanics replaced the CkPS itself, not the green signal wire from it. since the CkPS replacement is done w engine 'cold' , and the green signal wire integrity degrades only after an hour of driving at highway speeds, the test of wire integrity 'cold ' will not disclose the problem. and replacement of CkPS 3x did not solve the recurring p0300 s.
2/ did you view the entire Schroedinger's box YouTube ? if so you'd know that no one is testing anything w a socket wrench. the Schrödinger's Box you tube video clearly shows and explains all the tools he used to run the test to find the fault in the Crank position sensor's green signal wire. his replacement of the green signal wire cured the P0300 random cylinder misfire.

Sounds like you got it all figured out, sorry I couldn't comprehend your logic. Guess I'm just not playing in the same league...
I'm happy that your idea of changing the signal wire fixed your truck and I regret that I couldn't assist you, but it seems like you knew exactly what the problem was any way. Good work!

2/ did you view the entire Schroedinger's box YouTube ? if so you'd know that no one is testing anything w a socket wrench. the Schrödinger's Box you tube video clearly shows and explains all the tools he used to run the test to find the fault in the Crank position sensor's green signal wire. his replacement of the green signal wire cured the P0300 random cylinder misfire.

Actually, that's not at all how the video played out. If you pay attention, Matt was not diagnosing a p0300. This truck had codes that directly related to the CKP sensor circuit.
I am impressed that this repair worked for you considering you have different trouble codes and symptoms.