I searched and came up with zilch, so new thread:

How can I test my DBW throttle body off the vehicle? I had to replace the TPS sensor since it was broken off, but while I was doing it realized that water got into the housing. I'd like to make sure the TB still works before I put any more effort into making DBW work. (04 Rainier LM7 5.3 going into a 72 Chevelle)

I'm in the process of wiring my harness now, but not to the point of putting power to the PCM and actually making it work with the pedal. Also I'm still missing the harnesses that go from pedal to TAC and from TAC to TB.

It looks like this inside: http://i1255.photobucket.com/albums/...ps676665b6.jpg

 

It would be easier if the wires on your pigtail were color coded, but in any case the original yellow and brown are the 2 power wires. Those are position 4 in the plug for yellow and position 2 for brown. Ground the throttle body and tap 12 volts to the 2 pins. This should make the throttle plate snap open.
Look at www.eficonnection.com for the harness components. As I recall they have both fully assembled.

 

Thanks. Just to confirm, it needs 12v to both pins to open the throttle?
I was worried it was a stepper motor and I don't want to fry the poor thing.

 

In my experimentation I had 12V constant to the yellow and just tapped 12V to the brown. That should be enough to snap the throttle plate. Someone else may have a better procedure, but this should let you know that the motor works.

 

Whatever you do, do NOT put your fingers in there. Almost made that mistake doing a prestart on mine. Wow, that thing slams shut!

 

Okie Dokie, something's wrong. First let's check I did everything you guys said: I am using my 12V jump box as a power supply. Fully charged.

1. Grabbed the brown wire and the yellow wire (I have the connector ready on the harness, so it is color coded)

2. Confirmed that they go to the right pins in the connector per the connector diagram here: http://chevythunder.com/drive_by_wir...hrottle%20Body a little ways down is the image showing the 03-08 TB connector. Yellow and brown wires are TAC control 1 and 2.

3. Clamped the negative clamp of the jump box to the throttle body and confirmed that it had continuity from the clamp to the metal of the TB.

4. (Keeping my fingers well clear) Touched the brown and yellow wires to the part of the jump box positive clamp that has the cable attached to it.

5. Got nuthin.

Since I had already replaced the sensor, I pulled it off again, and I see that there are two terminals sticking up from the motor that go into connectors in the shell of the sensor. Confirmed with beeper on ohmmeter that these are the pins to which the yellow and brown wires attach.

6. (keeping fingers clear) Tried touching +12V(dc) to these 2 terminals.

7. Still nothing.

Now, I'm looking at this thing and there doesn't appear to be any way for the motor to ground if those are both positive terminals. The TB s attached to a plastic manifold, there is no third connection from either of the two low reference pins in the connector that would provide a path to ground.

What am I missing? :/

 

The Tan, and yellow wires just goto 12 volts. The t/b sits with the blade open approx 10%.
When you apply power the motor turns in one direction, when you reverse polarity it goes in the other direction. only do this for fraction of a second. Steve

 

Makes sense now. + to one wire, -to the other and whap! Switch them, and whap! The other way. Very nice.

Now I can proceed with the rest of the wiring and installing.

Thanks guys!

 

I got the car running. Build thread here: Chevello II

When I first started it there were no problems. Then after letting it sit for a day, the DBW issues began. First it set DTCs P1516, P.0120 and P0220. I started checking wires and found one that I heatshrinked before I soldered it. Oops. Fixed that and still getting issues.

Sometimes when I first start the car, I get a check engine light and no response from the throttle pedal. If I shut down, clear codes and restart, no problems. It drives just fine and I can't make the throttle drop out. If I work the pedal with the car off, I can stomp the pedal to WOT and it works, but if I slowly press the pedal I can hear the blade begin to flutter a bit and then it stops working, the blade closes and the check engine light comes on. If I clear the codes it works again, but does the same thing.

Now is where it gets weird. If I start the car with the pedal working, shut the engine off and immediately turn the key back on, nothing I do will make the throttle stop working again. I can stomp the pedal, slowly press it, tease it, tickle it, whatever. It always works. BUT if I walk away for 5 minutes, turn the key on without starting it, it will drop out if I slowly press the pedal again.

It's the weirdest damn thing and it's driving me nuts since I don't feel like I can take the car on any long jaunts for fear of the throttle either quitting altogether and not coming back if I clear the codes, or dropping out while I'm driving.

I should note that sometimes (I haven't determined the conditions) my cheapy Scan tool shows 100% throttle with the pedal at ~50%, and other times, it shows 100% at 100% pedal travel.

I've rung out all the wires several times, triple checked for proper pin placement in all the connectors and tested the pedal with my oscilloscope to make sure that the APP sensors are operating smoothly without any glitches.

I've also been searching the internet for fixes, and can't seem to find any threads anywhere where the OP actually comes back and says "Problem solved, it was XXX" unless the OP started from a completely dead throttle. Does everyone just give up after a while?

The engine is an 04 LM4 from a Rainier, the PCM, TAC and pedal are all 04 Silverado 1500 items and the PCM had the emissions and VATS removed by LT1Swap.com. Trans is the TH350 that was already in the car.

 

Like you I have one horror story after another trying to get my setup to work. Little did I know that the ECU was reprogrammed with an '05 tune and my '03 stuff would not work correctly. I could drive it as long as I didn't go above about 30% throttle, if I did it would go to limp mode and give me a U0102 code (I think) which is used as a data link for the DBW. Finally tried a friends TAC and pedal...everything worked! Found I had to get TAC #12588923 and an '05 Yukon metal pedal. Trick is to get a pigtail to connect the two. PSIconversions have the pedal and pigtail. Hope this helps. At any rate, let us know what you figure out because, like you say, nobody completes the loop when solved.

 

I'll have to look and see what tune is in there. I assumed that all the guy did was pull the alerts out for the emissions and rear O2 and disable VATS, but I don't know for sure. He could have a standard tune that he just uploads into all the PCMs he does.

I have a metal pedal that the part number crosses with the 05 Yukon, so maybe it's a TAC issue. I'll check to see if the number I have matches What worked on yours.

One of the things I did was have my son slowly press the pedal (engine off) while I watched the blade. as it came open, at one point it began to flutter right before it slammed shut. It makes me thing either the motor is having an issue at that point, or the TPS has a glitch at that point. I'm checking that today, and rewiring the TB connector today.

I'm just happy I didn't have a rod knock when I started it the first time, so these are minor issues I can sort out over the cold months.

 

I found that pedal 15821777 which is plastic, will also work with the 923 TAC. Big difference is the pigtail. The pedal end is different on just about all of the pedals but all plug into the TAC the same. Painless list pedal 15264643 with their harness.

 

Pulled the TB and started checking the resistances of the TPS sensors using a 5VDC power supply and an oscilloscope. Both TPS sensors were smooth without glitches. Checked teh resistance of the motor winding and Huh. Infinite. When I put the beeper on it, it only had continuity at certain positions of the blade. aHA!

Since I had replaced the TPS sensor it was easy to remove, so I pulled it and figured I'd pull the motor and clean things up. Couldn't get it out, but in my manhandling and spraying with PB Blaster, I began to get continuity through the windings at all times. Fiddled with it some more and put it back on. Can't get it to fail anymore.

So it looks like I need a new TB at least. This doesn't fix the 50% throttle thing though so maybe a new TAC will cure that issue. The TAC module I have now is #12573059.