Towing = low RPM 'shuddering' + flashing check engine light
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Cadillac SRX First Generation Forum - 2004 - 2009 Discussion, Towing = low RPM 'shuddering' + flashing check engine light in Cadillac SRX Forums; 2008 V8 w/V92 I was towing this past week and had three instances of low RPM 'shuddering' or 'pulsing' that ...
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    JayTF1 is offline Cadillac Owners Member
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    Towing = low RPM 'shuddering' + flashing check engine light

    2008 V8 w/V92

    I was towing this past week and had three instances of low RPM 'shuddering' or 'pulsing' that lasted approx. 10 seconds. The check engine light was flashing and then cleared once the vehicle was operating normally.

    No DTC's found with an enhanced scan tool. No other driving symptoms noticed.

    After a forum search my best guess is a sticking torque converter. I'm going to attempt a filter, and fluid change in the transmission. Any other suggestions?

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    nascarnation is offline Cadillac Owners Fanatic
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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    My experience base is getting old, but I thought it took a good number of drive cycles to erase codes.
    That's the key to diagnosing intermittants.
    Perhaps one of the techs on here will chime in.

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    rlh6805 is offline Cadillac Owners Fanatic
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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    Flashing check engine light = type A misfire occurring. That is the only thing that will flash that light. What brand and model scan tool were you using to pull the codes?

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    JayT F1's Avatar
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    Quote Originally Posted by rlh6805
    Flashing check engine light = type A misfire occurring. That is the only thing that will flash that light. What brand and model scan tool were you using to pull the codes?
    I thought it was strange that there was no codes.

    Innova 3100 was the tool. Checked for regular codes and gm specific enhanced dtc's

    Another thread mentioned the torque converter issues would cause a misfire scenario. I guess it could be a coil pack as well......

    Drove the car all day today with no issues.(non towing)

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    rlh6805 is offline Cadillac Owners Fanatic
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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    Quote Originally Posted by JayT F1 View Post
    I thought it was strange that there was no codes.

    Innova 3100 was the tool. Checked for regular codes and gm specific enhanced dtc's

    Another thread mentioned the torque converter issues would cause a misfire scenario. I guess it could be a coil pack as well......

    Drove the car all day today with no issues.(non towing)
    That is an shade tree mechanic scan tool. It's ok, but may not have the capability to send the ecu the correct DTC request. A proper scan tool will have the capability to read the misfire counter pids so a tech can see the cylinder(s) misfiring live. There may not be any codes set currently but there will be some in history that don't clear unless a clear codes command is sent to the ecu. The vehicle has an issue where one or more of the cylinders misfires during heavy load conditions (towing). You should get it checked out professionally.

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    JayTF1 is offline Cadillac Owners Member
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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    Thanks for the reply.

    As a side note, what is an option for an over the counter tool that can accurately diagnose our vehicles?

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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    I'm going to hazard a guess that you were in cruise or light pedal. What happened is the torque converter lockup solenoid was chattering (sticking). Can be avoided by heavier pedal application. New fluid will go a long way to correct. And any type A code will cause flashing light and that means get service right away- unless the light goes away.
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    rlh6805 is offline Cadillac Owners Fanatic
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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    Quote Originally Posted by glake89 View Post
    I'm going to hazard a guess that you were in cruise or light pedal. What happened is the torque converter lockup solenoid was chattering (sticking). Can be avoided by heavier pedal application. New fluid will go a long way to correct. And any type A code will cause flashing light and that means get service right away- unless the light goes away.
    This is not true. Type A refers to the misfire type not the code type. I am 100% positive that the ONLY thing that will cause the light to flash is a misfire. I write diagnostic scan tool code for a major OE so I know what I am talking about.

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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    I stand corrected, my excuse, just finished a 4 HR drive, top down,>90deg.
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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    Trans Fluid and filter booked at the shop on Wednesday. I'm going to swap the plugs with new Delcos and inspect/test all the Ignition Coils for good measure. I'll report back as I plan on towing again this weekend.

    Glake is correct that I was in a light throttle position when the problem occured.

    How long will a plug change take me with the V8?

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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    A "type A" DTC is a emission related code that lights the CEL and stores a freeze frame DTC after one failed driving cycle. A"type B" DTC is a emission related code that sets a pending DTC after one failed driving cycle and clears after one successful driving cycle. It will light the CEL and store a freeze frame DTC after two failed driving cycles.

    Bill

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    With transmission service complete at gm dealer, i towed a ~2600lb load in extreme heat for 4 hours today. No relapse of the symptoms. Problem solved? Perhaps........

    Spark Plugs ordered from rockauto.com for good measure. (Great prices on the delcos btw.)

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    PJ1520 is offline Cadillac Owners Connoisseur
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    Re: Towing = low RPM 'shuddering' + flashing check engine light

    Glad the fix was this easy. It must be a relief! PJ

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