Surging at 60 mph
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Joined: Apr 2018
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From: Sacramento
I took out the switch for the overdrive to make sure it is not a faulty switch if it isn’t the switch it is probably the overdrive solenoid is going bad. No codes to be found because it is going in and out of overdrive and that will not throw codes since it is apart of normal operation to be on or off. Well I’ll post when I have it fixed. Yes it is worth the trouble of fixing because it runs great otherwise.
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From: Sacramento
My mechanic said it was something internal that was making slip out of overdrive. Did adjustments with the bands help?
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Rookie
Joined: Apr 2018
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From: Sacramento
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Rookie
Joined: Apr 2018
Posts: 61
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From: Sacramento
chicken or the egg....failed smog or the transmission failed...
So I've kind of stumped could there be another reason other than the overdrive being bad and whole transmission needs to be replaced?? I had it smogged and it failed NOX at 55+MPH could this be related to the overdrive slipping or is it the engine not cooling right effecting the overdrive to shut off? I know I'm grasping at straws I just don't want to start getting knee deep in rebuilding this transmission only for it not being the issue.
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Joined: Apr 2010
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From: Clayton MI
Need to do some data logging, and see what the PCM thinks is going on.
According to theory, PCM will request overdrive when speed is above 45mph, engine load below some value, (which is likely pretty high.....) and trans fluid is over 108 degrees. On the older trucks though, very few of them had a trans temp sensor, so, I don't think that bit is an issue. PCM engages O/D by grounding the O/D solenoid control circuit. If it doesn't see the requisite RPM drop when it does so, it'll set a code. Since yours doesn't seem to be setting a code though...... that would tend to imply that the PCM is PURPOSELY dropping you out of O/D........ or, the TV cable is causing it. (in which case, the PCM would be seeing engine load going up, so, it would eventually drop it out anyway......
So, things to watch would be values for engine load, TPS, and O/D request....... See what is happening on those when the problem presents itself.
According to theory, PCM will request overdrive when speed is above 45mph, engine load below some value, (which is likely pretty high.....) and trans fluid is over 108 degrees. On the older trucks though, very few of them had a trans temp sensor, so, I don't think that bit is an issue. PCM engages O/D by grounding the O/D solenoid control circuit. If it doesn't see the requisite RPM drop when it does so, it'll set a code. Since yours doesn't seem to be setting a code though...... that would tend to imply that the PCM is PURPOSELY dropping you out of O/D........ or, the TV cable is causing it. (in which case, the PCM would be seeing engine load going up, so, it would eventually drop it out anyway......
So, things to watch would be values for engine load, TPS, and O/D request....... See what is happening on those when the problem presents itself.
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Joined: Sep 2013
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It occurs to me that a motor in poor condition might cause the PCM to sense the need for a shift
If you failed NOX you need to do some basic stuff to the motor, oil change, plugs, cap, rotor, wires. If you already did that right before the SMOG check then maybe the plenum gasket is leaking or something else is not optimal. ?CAT?? Doesn't Ca SMOG check law require that the person who sold you the vehicle pass a SMOG before selling it? Or did you wave that ? You are lucky to be in Sac there are a LOT of great junkyards in the area.
EDIT
Do you do your own oil change? If you do I have a method I got from an Aussie who swears he has done this to all of his vehicles all his life. I did it to my Dak and my little truck no ill effect.
Your Mileage May Vary
warm it up and drain the oil,
remove the filter and drain it put the used filter back on.
add two quarts of new oil and 1/2 quart of diesel fuel. Yes to the oil.
Drive as normal for a day. (I drove my Dak for a hundred miles on the highway the same day and did the rest.)
Warm it up drain the oil and replace with new filter and full amount of new oil.
This is meant to clean up gunk and help valve seals stay soft.
If you failed NOX you need to do some basic stuff to the motor, oil change, plugs, cap, rotor, wires. If you already did that right before the SMOG check then maybe the plenum gasket is leaking or something else is not optimal. ?CAT?? Doesn't Ca SMOG check law require that the person who sold you the vehicle pass a SMOG before selling it? Or did you wave that ? You are lucky to be in Sac there are a LOT of great junkyards in the area.
EDIT
Do you do your own oil change? If you do I have a method I got from an Aussie who swears he has done this to all of his vehicles all his life. I did it to my Dak and my little truck no ill effect.
Your Mileage May Vary
warm it up and drain the oil,
remove the filter and drain it put the used filter back on.
add two quarts of new oil and 1/2 quart of diesel fuel. Yes to the oil.
Drive as normal for a day. (I drove my Dak for a hundred miles on the highway the same day and did the rest.)
Warm it up drain the oil and replace with new filter and full amount of new oil.
This is meant to clean up gunk and help valve seals stay soft.
Last edited by onemore94dak; Apr 28, 2018 at 10:05 AM.
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Joined: Mar 2018
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From: Michigan
Adjusting the band only helped with the slippage in reverse.
id use marvel mystery oil instead of running the truck with diesel in the oil, but that's just me.
Definitely do all the tune up stuff, add a bottle of cataclean to a tank of premium gas and run through that whole tank. I'd use premium gas next time you do your smog test as well. I've managed to pass a couple cars through like that when I was living in az
id use marvel mystery oil instead of running the truck with diesel in the oil, but that's just me.
Definitely do all the tune up stuff, add a bottle of cataclean to a tank of premium gas and run through that whole tank. I'd use premium gas next time you do your smog test as well. I've managed to pass a couple cars through like that when I was living in az