Transmission Shifting Anomalies Allison 3000
Posted 09 October 2012 - 08:28 AM
Operating conditions: In cruise control, economy mode, pac brake off, 59 miles/hr (1550 RPM's).
Yesterday while traveling through the rolling hills of Missouri.....I noticed that on some hills the usual smooth shift from 6th gear to 5th was quickly followed by a jerking motion as if it really wanted to go into 4th (it did not go there). This happened several times in my 170 mile journey. I have Silverleaf, what parameters should I monitor to gather more pertinent detail.
I took it out of Economy mode...same result.
Took it out of Cruise and did not notice the problem.
Thanks for your help.
Posted 09 October 2012 - 11:25 AM
It turned out to be a problem with the Alternator voltage regulator(s). They put out a noise signature on the 12 volt wiring.
Good test-- take a drive and see if the cruise control works when engaged. If it works fine, drive for a period of time. Disengage the cruise and then reengage it. Do you notice the same issue with the transmission?
Note, at times it takes over an hr. for the problem to reappear.
I run silveleaf and now monitor the 12 volts to see if the voltage remains stable, if it starts to vary and the little green indicator in the voltage window changes from green to yellow or to red, suspect the alternator.
I would also have an issue with the speedometer jumping or varying and the tachometer reading would remain the same. Speed reading would change from 60 to 70+ or down to 50 or less.
Just my observations. Rich.
You could look in the photo gallery and look at my pictures and text regarding alternator and ignition issues.
Posted 10 October 2012 - 12:31 PM
Dianne and Brett Wolfe
1997 Safari Sahara 3540
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Posted 10 October 2012 - 05:04 PM
Update.....try bad fuel....the jerks and glitches became more frequent and under varying conditions. At about 1/4 tank of fuel I gassed up and almost immediately there was a change. After about 100 miles the problem was gone altogether. I am about to change the filters.
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