code 340 on 5.7L V8
November 10th, 2018 | 7:37 PM
#1
Thread Starter
CF Beginner
Joined: Nov 2018
Posts: 4
Likes: 0
code 340 on 5.7L V8
Got a tough one. Fair mechanic, but stumped. Have 5.7L GMC suburban with 150K miles, 1999 and has been a great vehicle. Started shifting a bit rough but just threw a code 340 camshaft sensor "communication". So easy fix first replaced camshaft sensor...same code...but fixed amazingly an idle problem I had where wouldn't come down from 12-1500 rpm till full stop? Now drops to 800 as it should?
So then replaced timing chain/sprokets. Another big improvement and seems torun great. Old one lots of slack so needed it.
So all good...but still throws code 340 immediately after erasing, many times. Any ideas of next directon or live with it???
thanks all
So then replaced timing chain/sprokets. Another big improvement and seems torun great. Old one lots of slack so needed it.
So all good...but still throws code 340 immediately after erasing, many times. Any ideas of next directon or live with it???
thanks all
November 11th, 2018 | 1:05 AM
#2
CF Monarch
Joined: Oct 2017
Posts: 4,605
Likes: 263
From: USA
Got a tough one. Fair mechanic, but stumped. Have 5.7L GMC suburban with 150K miles, 1999 and has been a great vehicle. Started shifting a bit rough but just threw a code 340 camshaft sensor "communication". So easy fix first replaced camshaft sensor...same code...but fixed amazingly an idle problem I had where wouldn't come down from 12-1500 rpm till full stop? Now drops to 800 as it should?
So then replaced timing chain/sprokets. Another big improvement and seems torun great. Old one lots of slack so needed it.
So all good...but still throws code 340 immediately after erasing, many times. Any ideas of next directon or live with it???
thanks all
So then replaced timing chain/sprokets. Another big improvement and seems torun great. Old one lots of slack so needed it.
So all good...but still throws code 340 immediately after erasing, many times. Any ideas of next directon or live with it???
thanks all
November 11th, 2018 | 7:58 AM
#4
CF Monarch
Joined: Oct 2017
Posts: 4,605
Likes: 263
From: USA
Depends. eBay has this one that is custom tuned to your VIN #
https://www.ebay.com/itm/Sierra-1500-1999-99-Engine-Computer-ECM-PCM-9354896-Programmed-to-your-VIN/312081966199?hash=item48a988e477:g:bOAAAOSw9mFWG9l ~:sc:USPSPriority!95667!US!-1:rk:37
f:0&vxp=mtr
https://www.ebay.com/itm/Sierra-1500-1999-99-Engine-Computer-ECM-PCM-9354896-Programmed-to-your-VIN/312081966199?hash=item48a988e477:g:bOAAAOSw9mFWG9l ~:sc:USPSPriority!95667!US!-1:rk:37
f:0&vxp=mtr