I bought a 2006 trailblazer with a 4.2 v6. Previous owner had replaced throttle body as well as ignition switch. Still have codes for both. I checked continuity in wires between throttle body plug and pcm and all wires tested good. Tried another known good throttle body with no change. Replaced pcm and it didnt seem to change anything. Still have p2101 code. Also cant figure out what else would be causing the p1682 code with the ignition switch circuit fault Any tips are appreciated.
Rough idle, with p2101 code
- Thread starter Tstorms10
- Start date
Also after replacing the pcm i got a p0315 code for crank position sensor system variation not learned. I am unable to do the crank sensor relearn due to the vehicle not allowing me to hold the brake and rev the engine at the same time.
Mooseman
Moderator
P2101 Throttle Actuator A Control Motor Circuit Range Performance
P1682 Code - Ignition 1 Switch Circuit 2
Try disconnecting the fan clutch. Sometimes they fail and short out the 5v reference, which is on the same circuit as the throttle system.
p0315 happens for one of two reasons; the PCM is replaced or the crank sensor is replaced or disturbed.
I replaced the pcm. Reason for that is the person i bought the vehicle from said he put a known good throttle body in the vehicle. I tested wires from throttle body to pcm and they all tested good. When i would turn key on and hit pedal the throttle blade wouldnt move, nor did it move when actuated with a scanner. When i would try to actuate the throttle blade with a scanner a P0606 would pop up for PCM internal processor fault. That was my reasoning for replacing the pcm. But it didnt seem to fix the issue.
Any ideas on the p1682 code on the ignition? Also with replacing the pcm, how do i relearn the crank sensor? The snap on scanner im using wants me to have the vehicle in park/neutral with parking brake set and brake applied and Rev vehicle until fuel cutoff. But the vehicle wont let me rev with the brake applied. Also the vehicle is in reduced power which i assume is either due to the ignition or throttle body code
A Few Scenarios for Probable Causes of the P1682 Code:
(1) A Fuse Contact Issue:
Notice the Dirty Conditions of the Uncovered Fuse Box as an invitation for Electrical Problems caused by the invasion of Dirt and Junk into the Fuse Insert Points making for Very Sketchy Electrical Pathing:
(2) A Broken Harness Wire 'Twixt The Fuse Box and The PCM:
On the chance that you are looking for a Broken Harness Wire, this Video should prove helpful with Solving the Code P1682 Problem. Follow the VOP's (Video Original Poster) Step-By-Steps He used ALLDATA Diagrams here and watch him conduct some logical diagnostic steps to achieve this Repair:
Please take note of just how THIN & Fragile the Wiring in those Harnesses can be and know that the Ordinary Engine Gyrations of the Engine's Rise & Fall of RPM and Torque while riding upon Bad Motor Mounts can invite problems of having Hidden Broken Wires like these.
(3) Replacement of the Fuse Block SOLVES the P1682:
In an Alternative Scenario, "Terry" provides us with a pretty lengthy description of what lead him to Replace the Entire Fuse Box (Panel) in his Performance LS Flavored Trailblazer and solved his P1682 Problem:
If there are any differences between the Wiring Harnesses and Connectors for Non-P-10 PCMs and your present PCM, I'm dropping a Link below, so you can view the 'Old Style" PCM Connector Pin-Out Diagrams. Just follow the VOP's Procedures, but use the more Relevant Wiring to Pin-Out Diagrams instead:
Check Out Post #4 HERE for the PCM PIN-OUTS:
gmtnation.com
Also... Check Out THIS Thread (Courtesy @Realism) for the Engine & Body Grounds and Bonding Strap Locations:
gmtnation.com
(1) A Fuse Contact Issue:
Notice the Dirty Conditions of the Uncovered Fuse Box as an invitation for Electrical Problems caused by the invasion of Dirt and Junk into the Fuse Insert Points making for Very Sketchy Electrical Pathing:
(2) A Broken Harness Wire 'Twixt The Fuse Box and The PCM:
On the chance that you are looking for a Broken Harness Wire, this Video should prove helpful with Solving the Code P1682 Problem. Follow the VOP's (Video Original Poster) Step-By-Steps He used ALLDATA Diagrams here and watch him conduct some logical diagnostic steps to achieve this Repair:
Please take note of just how THIN & Fragile the Wiring in those Harnesses can be and know that the Ordinary Engine Gyrations of the Engine's Rise & Fall of RPM and Torque while riding upon Bad Motor Mounts can invite problems of having Hidden Broken Wires like these.
(3) Replacement of the Fuse Block SOLVES the P1682:
In an Alternative Scenario, "Terry" provides us with a pretty lengthy description of what lead him to Replace the Entire Fuse Box (Panel) in his Performance LS Flavored Trailblazer and solved his P1682 Problem:
If there are any differences between the Wiring Harnesses and Connectors for Non-P-10 PCMs and your present PCM, I'm dropping a Link below, so you can view the 'Old Style" PCM Connector Pin-Out Diagrams. Just follow the VOP's Procedures, but use the more Relevant Wiring to Pin-Out Diagrams instead:
Check Out Post #4 HERE for the PCM PIN-OUTS:
BCM pinout
Looking to pick up on the reverse lamp circuit at the BCM. I've found sources that indicate it may be a light green wire, but there are several of them back there. One of which is a com wire that didn't take kindly to having a test light on it... anyone have a pinout for the connectors or a...
gmtnation.com
Also... Check Out THIS Thread (Courtesy @Realism) for the Engine & Body Grounds and Bonding Strap Locations:
Electrical Ground locations
While troubleshooting a bad ground I came across some scans of the service manual regarding electrical ground locations for our platform posted on another site. This includes both short and long wheel base, as well as both 4.2L and 5.3L. Credit goes to Wex...
gmtnation.com
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Mooseman
Moderator
You won't be able to do the CASE relearn until you resolve the other issues. This will not prevent the engine from starting or running. It's only to indicate when the timing chain has stretched too much.
@mrrsm has given you several leads and I would definitely back probe the PCM pins for both 12V and grounds going in as well as 5V references going out.
Also, did you check the ignition switch outputs? Even if new, it could be a dud or there is an issue upstream from it.
@mrrsm has given you several leads and I would definitely back probe the PCM pins for both 12V and grounds going in as well as 5V references going out.
Also, did you check the ignition switch outputs? Even if new, it could be a dud or there is an issue upstream from it.
...and if you follow up with @Mooseman 's suggestion to Probe the GMT360 (IGN) Ignition Switch Circuit, Eric "O" from SMA (South Main Auto) has presented us with a Very Nice Video on doing just that from around the 7:00 Minutes Point into this Diagnostic of a Trailblazer suffering from a 'No Start - No Crank' Scenario.
You just can't ask for Better Ignition Switch Views than THESE:
And a Two Part Series on Diagnosing any Problems with the Ignition Switch following specific steps to make this determination:
You just can't ask for Better Ignition Switch Views than THESE:
And a Two Part Series on Diagnosing any Problems with the Ignition Switch following specific steps to make this determination:
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