Ayala444
New member
mite not be the same problem but i figured mine out and it was a dirty mlps i took it off and cleaned real good then cleaned the conection give it a shot
converter randomly unlocking
- Thread starter Pstroke96
- Start date
cowboy_dan
Member
The OBS trans shift position sensor can get flaky. When that happens, the PCM unlocks the converter and puts the trans in neutral. An easy check of this is to stand on the accelerator when it happens. If no go, then probably that's it.
The other thing to note is that when this happens, the TC lockup does NOT re-engage automatically. It will use the shift tables to decide what gear and if to lockup the TC when you get back on the skinny pedal.
The SD sensor is apparently somewhat more reliable as it uses a PWM or other digital signal to the PCM.
The other thing to note is that when this happens, the TC lockup does NOT re-engage automatically. It will use the shift tables to decide what gear and if to lockup the TC when you get back on the skinny pedal.
The SD sensor is apparently somewhat more reliable as it uses a PWM or other digital signal to the PCM.
Pstroke96
New member
the trans is definatley not going into neutral. it stays in gear, but when it does happen it is a momentary thing, i dont let off the go pedal it just does its thing then goes back to normal. but it unlocked on me on the highway again. i think the next step is to ditch the led tail lights just to totally take thoes out of the equation, hopefully this isnt a sign of bad things coming down the pike i cant afford a zf swap just yet LOL
also, where is the sensor? cleaning it couldnt do anything bad right?
cowboy_dan
Member
It's a riveted and semi-sealed sensor on the side of the transmission. The shift cable attaches to an arm on a shaft that goes into the transmission. The sensor is on that shaft and senses the rotational position of the shaft.
Pstroke96
New member
so its a bit of a project, is atf going to pour on my head when i take it out?
Ayala444
New member
hey man i didnt know u had led tail lights that mite be ur problem i think. my buddy put a flat bed on his obs and put leds and wen he would get on the pedal it would unlock but wen he let off it would lock back up also check ur manual lever position sensor and do have a trailer brake??
Tom S
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I believe that sensor is external.
cowboy_dan
Member
If ATF pours on your head when you take it off, then you either took the wrong thing off, or you have much, Much, MUCH, bigger problems.
Look on the LH side of the transmission where the shift linkage hooks to. It's a plastic box looking thingy with a connector on it. About 2.5" X 3" X .75"
jdgleason
Active member
Maybe a resistor or lack there of with the tail lights? Maybe voltage drop isn't where it needs to be and is messing with things? Just a shot in the dark
Ayala444
New member
that makes more sense since leds stay on all the time and require less voltage to operate leading less voltage drop
cowboy_dan
Member
Voltage drop stays the same. The LED lights require less current. If you hook up an LED to 12,000 volts, the voltage drop across the LED (for the nano second that it is on before it burns up) will be exactly 12,000 volts.
When LEDs lights are manufactured, there is a current limiting resistor that is installed with most of them. This resistor allows a an LED with a lower voltage rating than the system voltage to be used. So part of the system voltage is dropped across the current limiting resistor, and part of it is dropped across the LED.
A really good system to use LEDs will control the current and not worry about the voltage unless it goes outside a certain range. The current is the killer of LEDs, not the voltage.
Here's how it goes:
-Suppose you have an LED with a 20mA @ 2v rating (not at all unrealistic), and you're putting it in a circuit with a 14v supply.
-You have to limit the current and reduce the voltage, so 14v - 2v = 12v. So we have to drop 12 volts across the resistor.
-To determine the resistor size, it is 12v / 0.02A = 600 ohms. (20mA is the same as 0.02A)
The resistor that you have to add is a very low resistance compared to the current limiting resistors. The resistor you have to add is there only to increase the current that the circuit is using.
Say, you decide you need an extra amp of current draw to make the system work correctly:
That's easy! 14v/1amp = 14 ohms.
SoCalPSD
New member
Interesting, my e99 is doing the same thing on a reflash and about 300 miles on my rebuild. And my truck is pretty much stock with the exception of the intake.
Pstroke96
New member
thats a little over my head but im understanding most of it. the led's are retrosoloutions with their resistors as well. im going to take them out today and see what changes. if all is well they will stay gone.
Pstroke96
New member
well with the lights out it stopped for a while, but its doing it again. but now when it does it it will do it a 3-4 times in a row then be fine for a while. also while possibly un related it holds onto the 2-3 shift sometimes when im light on the go pedal it it will come up to where it will usually shift and hang there for a few seconds, then ill give it a little romp and it shifts. im driving to school now 40 miles each way every day so i have to be able to rely on it.
Pstroke96
New member
nobody?? bump
Pstroke96
New member
so low and behold i finally found my problem, where the wires went up under the back of the bed they were pulled tight in the flex loom and they chaffed against each other, causing the turn signal to power up both wires and unlock the converter. i loosened a few clips to get some slack cut the wires at the chaffed spot and reconnected them with shrink wrap butt connectors, all is well again. appreciate all the help guys
