Edmunds Answers

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  • MrShift@Edmunds 09/29/11 9:55 pm PST

    It is the upshift delay codes P1700 and P1701. These codes would only apply to the mechanically controlled automatic transmissions used before 1996. Those transmissions used a throttle pressure cable (control pressure) for determining shift points under various loading. In order to heat the CAT and reduce the cold running time, Mercedes used an electrically controlled, vacuum-operated bellcrank-type lever action to change the capabilities of the control pressure cable. In other words, when cold, vacuum at the switchover valve is switched to a vacuum chamber at the transmission end of the shift cable. There, the actuator movement changes the effective length of the cable. The common problem here is the diaphragm in the actuator element, but testing is simple.

    The first test is to see that vacuum is at the switchover valve when running. Next take the line to the transmission from the switchover valve and apply vacuum. In the common failure, the element won't hold vacuum, and you're done with diagnostics.

    If the vacuum element holds vacuum, then you must tee into the line at the element and evaluate the vacuum when cold. If there is vacuum at cold running, and a code is present, then evaluate the shift against the criteria. The element is adjustable on the replacements and the cable is always adjustable. A poorly adjusted shift cable adjustment could make the added shift delay not large enough to satisfy the controller.


    Source: continentalimports.com

  • alvafang 09/30/11 6:29 am PST

    you canvisit here.
    I think it will help you find out the problem and it is useful....

  • MrShift@Edmunds 09/30/11 10:51 am PST

    Thanks for posting but your link seems to be for code 170, not 1700. Am I missing something?

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