was this a factory ground at one point?
 

So i was poking around trying to see the "ecu Ground" on my block underneath my uim to try and fix my 3800 hesitation issue and noticed this.

http://i113.photobucket.com/albums/n...ad9821/wtf.jpg

Doesnt look factory to me, was there a factory ground there at one point? it looks like the insulation from the dizzy wiring or whatever was used as a ground..

oh and you cant see it very well but it leads to the other yellow connector grounded to the uim.

someone has joined the shield for the cas wiring to an earth point
seems to me they may have been chasing the hesitation issue

this is actually the wrong thing to do,,, for it should already ( correctly ) earthed at the far end and so work as a farady cage to collect RFI and feed it an easy path to ground

having it earthed at both ends somewhat kills the intended cage effect
and may instead force the CAS wiring to work as a conduit to balance earth potential between block and ground
this may infact introduce noise to the CAS signal wiring

under the UIM on turbos you should have a very decent earth wire bolted to top of the housing at the mounting point for the top mount brackets

the real fix for the usual staging issue is in repairing the crimped joins that bundle all the earth wires and shield together
,,, not far out from the ecu

cut that silly join from the CAS wiring and if you have hesitation issues on staging then instead repair the loom here-

i dont fully understand your write up, all the wiring repairs are being done very close to where it plugs into the ecu correct? theres a power wire bundle on my car black with yellow stripe correct? just resoldier that joint and re-tape/heat shrink it? then do the same on my grounds (all black wires on american cars still correct?) and at the end of your thread its saying to add another wire and make a new ground for it?

sorry for the million questions, i just want to measure twice and cut once!

Basically, cut that yellow connector off and remove the black wire where ever it is attached. It is not a factory ground. It is a very very bad idea whomever did that. After that continue your search for the stock factory grounds, and clean those up.

The grounds are shown in the two attached jpg below.

If you follow any of those ground wires from the ECU plugs up the harness (unwrap the tape around the harness like BUMPSTART says), you'll find three of those wires all spliced together with a mechanical crimp device. '

Add a new gnd wire to that mechanical crimp and also solder all them together at the same time. Then put a ring terminal on your NEW wire and terminate that new ring terminal at a known ground point. Like I used one of the studs that hold the ECU bracket to the chassis and that worked fine.

The wire out of 2D is the 02 sensors input to the ECU. That wire is the center conductor of a shielded cable. As you follow that black wire at 2D up the harness it will enter a GREY shielded cable. The SHIELD of that cable is also spliced to the ground wires of 3A, 3G, 2R. Make sure you don't actually ground the black center conductor coming off 2D to ground. Not good thing to do. Be careful.

Now take a look at my second jpg I attached. You'll see all those gnd wires off 3a, 3g, 2R all spliced together. See that???? The dotted line next to 2D represents the shield wire of the shielded cable for the 02 sensor. Take note.

NOW look where I drew lines in GREEN. Those green lines are the ground wires for the various sensors in the engine bay. So what this means is, that when you add a gnd to 3a, 3g, 2r, your also adding a gnd to the gnd wires for the sensors in the engine bay and also to pin 2C of the ECU which is the end point for those sensor grounds just mentioed. Just FYI.

At the very bottom of the second jpg page you'll see ground point 24. The number is very blurred in this jpg. That gnd point 24 is on top of the Rear ROTOR housing and is terminated with a ring terminal with two black wires if memory serves. Usually the problem is not that ground point but the problem lies with the mechanical crimps used inside the EM harness. That's why your adding a extra gnd wire to the three gee, two rrrrrr, three aaaaa about a foot up the plug harness from the ECU.

Aside from having some ugly soldering skills, i THINK my hesitation issue is gone. i want to drive on it more before i say it is for sure because the problem never seemed to be consistant.

Thank you for your help!

good info on here, i wish i could get a better picture

Bump that looks like my wiring nightmare GL man

So my hesitation issue was fixed by this for good if anyone was curious. Thanks again for the write up and pictures!