Fault Codes OBD question?
#11
01-13-2010, 09:07 PM
Join Date: Aug 2008
Location: Poconos, Pennsylvania
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What I was saying is that the '93 Dakotas had a cable driven speedometer, but also an electric speed sensor for the computer. The computer needs to know speed to control the IAC, cruise control, torque converter lockup, overdrive shift, etc. The cable driven speedometer and electric speed sensor is a all in one unit, just simply called the speed sensor. In '94, the took out the cable and let the computer run the speedometer through a step motor.
If your truck has cruise control, check to see that it still works, and if it does, there is nothing wrong with your speed sensor. Remember the computer stores old codes until it is reset, so there may not be anything currently wrong with your speed sensor.
There are several other reasons for the OD not to work, the speed sensor being one of those reasons. Another reason is temperature... the engine needs to be in closed loop before it will allow the 3-4 shift. Also TPS postion and MAP sensor reading effect it. Also a blown fuse or faulty wiring could stop it.
If your truck has cruise control, check to see that it still works, and if it does, there is nothing wrong with your speed sensor. Remember the computer stores old codes until it is reset, so there may not be anything currently wrong with your speed sensor.
There are several other reasons for the OD not to work, the speed sensor being one of those reasons. Another reason is temperature... the engine needs to be in closed loop before it will allow the 3-4 shift. Also TPS postion and MAP sensor reading effect it. Also a blown fuse or faulty wiring could stop it.
My Cruise control will not turn on unless I'm in OD and I proved that today because when my tranny shifted into 4th gear for like 30 seconds I quickly turned on my cruise control and then my tranny went back to 3rd gear it turned off. I know my fuses are all good and I never changed my MAP sensor. Right now I'm thinking it must be the engine temperature because that would explain why my tranny shifts bad when it's 0F to 45F degrees.
Thanks for the info I'm going to do some more testing.
#12
01-13-2010, 09:15 PM
Well with that last comment I'm really starting to lean toward a bad speed sensor. Cruise control should not be temperature dependant nor dependant on what gear the transmission is in, so if both OD and CC turn off at the same time, and your computer is throwing the speed sensor code, that would definately be where I'd start!
I have no idea why it would work fine in the summer and not in the winter though. The ECT sensor, thermostat, etc. are all things that should still be checked out, but I think the speed sensor is causing your OD and CC issues.
I have no idea why it would work fine in the summer and not in the winter though. The ECT sensor, thermostat, etc. are all things that should still be checked out, but I think the speed sensor is causing your OD and CC issues.
#13
01-20-2010, 07:05 PM
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just an update about my tranny problem.
I changed my O2 and my Air charge temperature sensor yesterday since both those sensor needed to be changed. No luck or change. I did a coolant change 4 weeks ago and I can't see how my engine isn't up to temp.
It seems like I will be going to a transmission mechanic since I'm out of thought.
I changed my O2 and my Air charge temperature sensor yesterday since both those sensor needed to be changed. No luck or change. I did a coolant change 4 weeks ago and I can't see how my engine isn't up to temp.
It seems like I will be going to a transmission mechanic since I'm out of thought.