I search the forums but couldnt find a "how-to" on soldering the GMTU TMAP sensors. So I thought I would post a couple pictures of what I did. This is for the lower tmap harness. I will post up the picutes for the upper tmap harness later tonight.
To access the lower tmap harness:
- jack up the car
- remove the front bumper

from under the car:
- remove the lower passenger side plastic cover (sits below the wheel well cover)
- remove the passenger side intercooler bracket
- disconnect the intercooler from the cold side pipe
- unbolt the passenger side radiator lower mount (3 bolts)
- disconnect 3 harness plugs to free up the TMAP harness
TMAP plug, A/C compressor plug, and recirculation switch? (round gray one)

from above the engine bay:
- loosen 8 mm/flathead screw on the worm clamp connecting cold side pipe to the throttle body

from under the car:
- pull the cold side pipe down off of the throttle body
- disconnect the vacuum line from the cold side pipe
- pull out the cold side pipe from the car
(have to push the radiator out of the way, takes some wiggling)

After all of the above you should now have enough room to access the TMAP harness from under the car. I did my soldering with rosin core solder and used adhesive backed shrink wrap. You will need a heat gun for the shrink wrap. There isnt enough room to use a lighter. I also flipped my TMAP sensor 180 degrees so the plug faces the radiator and not the motor.
There are already "how-tos" on removing the bumper, and flipping the lower tmap sensor on the forum.

This is what I started with. The lower tmap harness was pinched in between the AC compressor and the A/C hardline. Anytime the motor shift it will try to rip the wires out of the harness.


Bumper removed.


passenger side intercooler bracket


lower passeger side engine cover. The wheel well cover is the weird line in the middle of the picture.


2 rear plastic push clips for the lower enginer cover, they sit behind the wheel. You can reach them from under the car.


These are the 3 bolts for the passenger side radiator mount. Unbolt them so you can push the radiator and intercooler out of the way


Cold side pipe with the vacuum hose still connected, and the radiator pushed out of the way with my hand. Disconnect that hose, then pull the pipe out.


cold side pipe removed!


I had to sand off the tab to do the lower TMAP sensor flip. I used a dremel, but a hand file could work just as well. Make sure its sanded flat or the sensor will sit at an angle.


I cleaned the TMAP with alcohol and Q-tips. Then I used a Q-tip and brushed a light layer of motor oil on the blue O-ring.


Lower TMAP flipped! I didnt show it here but I use a little Loctite Blue on the 7mm bolt that holds the TMAP in place.

 

TMAP harness with everything out of the way and the electrical tape removed. The pictures dont convey how terrible the crimps were. It looked like the crimps were done with a pair of pliers. And none of it was heat shrunk.


This is all the harness i had left to work with. I had to solder on extensions for each wire for this to even work.


I thought about tinning the wiress and doing a parallel solder, but there just isnt enough room to make sure its all positioned properly. So i did a twist joint.


Soldered with adhesive backed heat shrink. If you look closely you can see the glue seeping out from under the adhesive like its supposed to, to complete the seal.


Here you can see all 8 solder joints. I did not want to have 2 solder joints back to back but I didnt have a choice since the harness was cut so short for the crimp connectors.


Everything soldered wrapped and bolted back in place. There is about a 1/2" of clearence between the radiator and the harness. I think that should be enough since the radiator does not move.

 

GREAT WRITEUP!!!

I noticed the reference to using loctite - I love Loctite, but be aware that loctite eats most paint and a lot of different plastics. Hopefully that won't be an issue with it here.

I've seen it melt plastic on motorcycle bodywork - and it ain't pretty. Don't ask whose -

 

This is how I soldered the top upper TMAP sensor. This one is easy to get to. I had the same issue on mine that there was very little wire left after I cut out the GMTU crimp. I soldered in an extension, then taped everything up.

GMTU crimps that were done by some dealership before I owned the car. Just nasty looking. These actually looked worse than the ones under the car. none of them were heat shrunk.


I cut the plug free. Pin 2 on the plug is unused.


Ready for solder


Extension wires soldered on


Now to attach the upper TMAP plug. Dont forget to slip the heatshrink on first.


Soldered and covered with adhesive heat shrink tubing. I used a cheap heat gun from harbor freight. I dont know how you could possibly do this with a lighter.


All taped up and plugged in.


I went for a test drive tonight, and its so far so good. No codes and boost is holding steady at 17psi. I should probably have more but I think the bypass valve is the issue now.

 

Thanks so much for putting this "How to" together. This is a huge help!!!

I would note a few things that may be of interest to others who use this.

It is not necessary to pull the front bumper off. This was a huge hurdle for me as it is a pain in the rear and easy to break the plastic clips that hold the bumper to the fender. I found it was easy enough to complete with the bumper in place.

The other thing is that if you are looking at the crimps and they look to be in great shape and done well, do yourself a favor and snip them off before you talk yourself out of it. Mine looked like they were in perfect shape and done correctly, sealed up well ect...But I went ahead with the repair thinking I was wasting my time. This repair solved my problem. My Red Rocket is back....and that is so awesome!