Chevy Trailblazer SS Forum banner

21 - 40 of 47 Posts

·
Registered
Joined
·
364 Posts
I have to get mine running right again on sunday. I havent had a chance to look at it yet because 6 days a week I work on everybody else's cars and only have sunday for my own.

Sent from my SM-G965U using Tapatalk
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #22
Why isn’t the truck starting and the shifter doesn’t move


Sent from my iPhone using Tapatalk
 

·
Registered
Saab 9-7X
Joined
·
620 Posts
Why isn’t the truck starting and the shifter doesn’t move


Sent from my iPhone using Tapatalk
Start with the PRNDL from the 4L70E and make sure it's in Park. If it's not connected and in the right position, you either won't be able to start, won't be able to move the shifter, or both. Since the positions aren't really fixed presets, I recommend using a meter to check the values below. I would up buying a new sensor for $20 because I couldn't find/get to the park position and that fixed it.

Tim

From my previous post:
Pins 1 and 12 of the sensor must have continuity to allow the car to start. This connection is continuous when the sensor is in Park and Neutral.
Pins 9 and 11 of the sensor must have continuity to trigger the Park Interlock. This connection is continuous only when the sensor is in Park.
100373


100374
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #24
Start with the PRNDL from the 4L70E and make sure it's in Park. If it's not connected and in the right position, you either won't be able to start, won't be able to move the shifter, or both. Since the positions aren't really fixed presets, I recommend using a meter to check the values below. I would up buying a new sensor for $20 because I couldn't find/get to the park position and that fixed it.

Tim

From my previous post:
Pins 1 and 12 of the sensor must have continuity to allow the car to start. This connection is continuous when the sensor is in Park and Neutral.
Pins 9 and 11 of the sensor must have continuity to trigger the Park Interlock. This connection is continuous only when the sensor is in Park.
100373


100374
So I should take apart my center console? Can you walk me through a little bit on what km testing for


Sent from my iPhone using Tapatalk
 

·
Registered
Saab 9-7X
Joined
·
620 Posts
I disassembled my center console as part of my troubleshooting, but my issue was under the car. Troubleshooting in the console only confirmed that I was missing voltage/continuity in a few places. Further troubleshooting via the wiring diagram led to the PRNDL switch. The switch I'm talking about came off of the input selector shaft on the 4L70E. Your shift cable attached to this shaft. The 6L80/6L90E does this internally, but a lot of the functions like the starter relay and park interlock are still tied in to the old sensor which you removed when you pulled the 4L70E. It needs to remain in the loop and in the Park position for the swap to work properly. There's likely a more elegant way to wire this than to re-use the sensor even though it's not connected to anything, but once I got it working, I quit looking for a better solution.

The part I'm talking about looks like this:
In the picture below, it's on the left hand side of my 4L60E. You can also see the 6L80E in the background without any provisions for this sensor.
100470


One more picture showing the sensor mounted on the 6L80E here:

Tim
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #26
I disassembled my center console as part of my troubleshooting, but my issue was under the car. Troubleshooting in the console only confirmed that I was missing voltage/continuity in a few places. Further troubleshooting via the wiring diagram led to the PRNDL switch. The switch I'm talking about came off of the input selector shaft on the 4L70E. Your shift cable attached to this shaft. The 6L80/6L90E does this internally, but a lot of the functions like the starter relay and park interlock are still tied in to the old sensor which you removed when you pulled the 4L70E. It needs to remain in the loop and in the Park position for the swap to work properly. There's likely a more elegant way to wire this than to re-use the sensor even though it's not connected to anything, but once I got it working, I quit looking for a better solution.

The part I'm talking about looks like this:
In the picture below, it's on the left hand side of my 4L60E. You can also see the 6L80E in the background without any provisions for this sensor.
View attachment 100470

One more picture showing the sensor mounted on the 6L80E here:

Tim
That’s awesome! That’s exactly what I assumed but so I will just plug that thing in and let it hang?


Sent from my iPhone using Tapatalk
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #28
Exactly. You should even be able to bolt it onto one of the housing bolts from the 6L80E. Check continuity as mentioned above before installing it to make sure it's in the right position internally.

Tim
Well all the way forward should do it right?


Sent from my iPhone using Tapatalk
 

·
Registered
Saab 9-7X
Joined
·
620 Posts
My factory one didn't have any detents. I don't know if it was broken or it's meant to be that way. The replacement switch I bought had a shipping piece that fixed it into park position. I kept this on it when I installed it because I didn't ever want it to lose its position again.

Tim
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #30
So how would you recommend I do it? Take it off the 4l70 and don’t move it?


Sent from my iPhone using Tapatalk
 

·
Registered
Saab 9-7X
Joined
·
620 Posts
That's what I would do. Put your 4L70E in park. Check the continuity of the pins as mentioned above. Remove without turning the center part that goes on the input selector shaft of the 4L70. Double check continuity of the pins, then attach back to your existing wiring harness and find somewhere to stash it.

Tim
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #32
So I just installed it and the shifter moves now but won’t start


Sent from my iPhone using Tapatalk
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #33
My tuner told me to ask around if the VIN in the trans needs to be changed to match the truck?


Sent from my iPhone using Tapatalk
 

·
Registered
Saab 9-7X
Joined
·
620 Posts
Check for continuity between pins 1 and 12 of the PRNDL switch.

It can be a bit tough sometimes sorting out what's a mechanical issue vs. a tuning issue. I certainly ran into a handful of these issues during my build and I usually found out the long/hard way which was right.

You shouldn't need to change the VIN on the transmission. What calibration are you using?

Tim
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #36
That’s what I was thinking? If all they do is make a connection when in a certain position


Sent from my iPhone using Tapatalk
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #38
So 9&11 don’t make continuity at all on the switch... if I’m doing this correct 12 is at the top of the sensor and one is at the bottom which means that 9&11 are furthest out from the trans... I have tried to treat 9&11 as if they may be on the side closest to the trans as well and still nothing


Sent from my iPhone using Tapatalk
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #39
Scratch that... 9&11 are closest to the trans and they do make continuity... why won’t it start!!!! Lol


Sent from my iPhone using Tapatalk
 

·
Registered
TrailblazerSS
Joined
·
40 Posts
Discussion Starter #40
Update...

The pins 1&12 as well as 9&11 have continuity and the connector is plugged in... I have power to my crank fuse under the hood when attempting to start but no power to the crank wire (#12) on the plug from the 4l70...

Where should I start...


Sent from my iPhone using Tapatalk
 
21 - 40 of 47 Posts
Top