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"Shifty" Sound


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pmarc
User

Aug 17, 2014, 5:06 AM

Post #1 of 12 (1581 views)
"Shifty" Sound Sign In

Between 1200 ans 2000 RPM occasionally, for several months, I get a jerk sound, like shifting gears. It's moderately rough. The guy who installed a rebuilt transmission 2 years ago said it might be the motor skipping. But another guy showed me a readout showing "transmission skipping".

(Reading between the lines, I believe my original guy doesn't like small jobs - and probably doesn't like re-do jobs post-warranty).

Anyway, any ideas what's really going on? When the jerking happens there is no extra load on the car. Just flat terrain, normal driving.

Car: 2007 Chevy Trailblazer


Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 17, 2014, 6:52 AM

Post #2 of 12 (1567 views)
Re: "Shifty" Sound Sign In

Hmmm - One says engine another thinks trans but this doesn't do this all the time. Get codes if nothing else with #s as if engine doing this is should know it.


Do you have a copy of this printout and what it really said?


T



Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Aug 17, 2014, 9:12 AM

Post #3 of 12 (1558 views)
Re: "Shifty" Sound Sign In

Why was a rebuilt transmission installed?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


pmarc
User

Aug 17, 2014, 2:35 PM

Post #4 of 12 (1551 views)
Re: "Shifty" Sound Sign In

Coolant got into the trans. Car inoperable.


GC
User
GC profile image

Aug 18, 2014, 6:20 AM

Post #5 of 12 (1539 views)
Re: "Shifty" Sound Sign In

This was the diagnosis? Ouch


____________________________________________________
Willing to help, willing to learn... Rob


pmarc
User

Aug 18, 2014, 6:24 AM

Post #6 of 12 (1537 views)
Re: "Shifty" Sound Sign In

Anyway, that's the past. Worked ok til now. Maybe not transmission now...
I'll bring to my regular guy today.


pmarc
User

Aug 19, 2014, 6:29 AM

Post #7 of 12 (1518 views)
Re: "Shifty" Sound Sign In

$150 fix with a new coil - did a scan at the transmission guy. said cyl #6 was mis-firing. so the motor problem was creating errant trans codes.

i ran the car, alot yesterday and no "shift" problem. i suppose this doesn't guarantee it's fixed, assuming something i can not feel is still happening? other codes at the trans guy: PO128, P1400 and the original PO894, PO300. a snap wasn't used, altho one may be accessible if we have to. trans oil is clean.


Discretesignals
Ultimate Carjunky / Moderator
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Aug 19, 2014, 3:40 PM

Post #8 of 12 (1509 views)
Re: "Shifty" Sound Sign In

You stated it has or had errant transmission codes? Usually misfires don't cause transmission codes to appear. What were the codes? Which engine? 2 or 4wd? If those codes are cleared, do they reappear?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


pmarc
User

Aug 21, 2014, 8:50 AM

Post #9 of 12 (1485 views)
Re: "Shifty" Sound Sign In

A simple scanner still shows PO 894. Their Snap is $95 per scan so I'll find another guy for no charge if poss. Car still sounds ok after another 140 miles.


pmarc
User

Aug 21, 2014, 11:57 AM

Post #10 of 12 (1479 views)
Re: "Shifty" Sound Sign In

Are there any "Snap" shops offering free scans? Took again to trans guy and he showed his scanner pulled up no codes. I need a report to show him. He tried the car again. It's an intermittent problem. He saw nothing. I saw nothing riding home but I did hear / feel the shift sound when riding to his shop. He says bring it in when I have something.


Discretesignals
Ultimate Carjunky / Moderator
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Aug 21, 2014, 3:50 PM

Post #11 of 12 (1468 views)
Re: "Shifty" Sound Sign In

There is a TSB on that. Did a transmission shop attempt to troubleshoot the trouble code?


Quote
INFORMATION

Bulletin No.: 08-07-30-008B

Date: June 03, 2008

Subject:
Diagnostic Information on Diagnostic Trouble Code (DTC) P0894 and P1870

Models:
2003 - 2007 GM Passenger Cars and Light Duty Trucks
2003 - 2007 HUMMER H2
2006 - 2007 HUMMER H3
2005 - 2007 Saab 9-7X

with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32 or M70)

Supercede:

This bulletin is being revised to remove the 2002 model year. Please discard Corporate Bulletin Number 08-07-30-008A (Section 07 - Transmission/Transaxle).

Diagnostic trouble codes (DTC) P0894 and P1870, Transmission Component Slipping, may have different root causes. The following diagnostic tips are provided to assist in accurately repairing the condition.

^ Corporate Bulletin Number 06-07-30-007 is intended for 2006 vehicles only. This bulletin provides diagnostic procedures to determine if the TCC enable solenoid is cracked.

^ Slip speeds ranging from approximately 100 to 400 RPM at steady state light load driving are usually caused by the TCC not applying.

^ Slip speeds greater than about 400 RPM at steady state driving are usually caused by a slipping clutch or band. Inspect the oil pan for the presence of excess clutch debris.

^ A plugged or restricted TCC apply fluid orifice (238, located in the pump) may cause DTC P0894 or P1870, especially in low mileage vehicles with less than 8,000 km (5,000 mi).

^ A converter clutch valve (224, located in the pump), which does not have full travel of 13 mm (0.5 in) or is stuck in the off position may cause DTC P0894 or P1870. Inspect the valve for chips, debris, nicks or burrs. Also, inspect the springs (225 and 226) to make sure they are not limiting valve travel. A spring that is not fully wound may catch in the bore, limit valve travel and cause DTC P0894 or P1870.

^ A cut, damaged or missing turbine shaft O-ring seal (615) may cause these DTCs. When installing this O-ring to the turbine shaft, make sure it is fully seated on the groove all the way around the turbine shaft and can be easily rotated with the thumb and forefinger. Failure to fully seat this O-ring may result in cutting when the torque converter is installed.

^ A cracked or leaking TCC solenoid (part of harness 66) may cause DTC P0894 or P1870. Use solenoid test kit J 44246 to test the operation of this solenoid.

^ A cracked or leaking TCC PWM solenoid (396) may also cause DTC P0894 or P1870.

^ If the vehicle has 24,000 miles (38,600 km) or more, and diagnostics have not determined another cause of the DTC, the torque converter should be replaced.

When attempting to diagnose a DTC P0894 or P1870, it is important to also refer to the appropriate Service Information (SI) document for further possible causes of this condition.






Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


pmarc
User

Aug 25, 2014, 4:36 AM

Post #12 of 12 (1438 views)
Re: "Shifty" Sound Sign In

re: "Did a transmission shop attempt to troubleshoot the trouble code?"
answer: No.

Since the problem may NEVER show itself when a mechanic is driving my car since the problem is intermittent, I am getting a full Snap diagnostic fro $74, today.

Q. Am I correct to assume the report from the $74 Snap diagnostic will effectively troubleshoot the problems to a level that will substitute for any mechanical exploratory time by a mechanic?

Also, in any event, it seems I need the detail diagnostic so I, and others, can act correctly. We need better information that what we have right now. BTW - the only warranty I got was verbal. Stupid me. So why in heck this guy is even bothering to talk to me, and doing his own scan, and riding the car, I'm not sure. Maybe he's just being ethical, or more likely he wants these good-faith efforts to accompany him to court if that's where we end up. By the way a lemon law lawyer in Mass says I have a weak potential for recourse.


(This post was edited by pmarc on Aug 25, 2014, 5:18 AM)






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