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Discussion Starter · #1 ·
My DBW doesn't respond, and it's because I don't have the C1-14 & 15 wires hooked up. Where do they go? I have searched, but no luck.
The only drawing I have shows them going to the TAC, but the only wires I have is the short harness from the TAC on the pedal to the TB plug-in.

Thanks...
 

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Discussion Starter · #3 ·
After further investigation, let me ask: howdo you "power" DBW if you don't use Cruise Control?
It looks like the TAC is used for DBW and CC together.
??

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Discussion Starter · #4 ·
The engine, w/DBW, pedal assy. wiring harness.. everything all came off of a 2004 Silverado 2500 6.0L.

I have the harness from TB to pedal assy. but I don't know what actually "powers" it all. I don't have the TAC that mounts on the firewall, and I have the C!-14&15 wires from the PCM that go to ??.

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Discussion Starter · #7 ·
Is the TAC module a "reliable" component? I mean, can you buy a used one or just suck it up and buy the new one?
Also, does anyone have the harness that goes between the pedal and the TAC module? I only have the one from the TB.

I have the C!-14 & 15 wires from the PCM to power it, so it looks like the truck I got everything had the TAC module, they just didn't give it to me....RATS!
 

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Discussion Starter · #9 ·
Just occurred to me. The TAC module isn't specific to the pedal assembly, is it?
If you just buy the TAC there isn't any "re-programming" involved, right?

Dumb question... ? But, I had to ask...
 

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Discussion Starter · #15 ·
OK, I have retrieved the original TAC module and pedal to TAC cable. (guy still had the “remains” of the truck everything else I have, came from). WOW!

Anyway, I installed everything and verified TAC wiring from PCM and “power” from UBEC –C2 was connected.

The engine will start, but will idle very low RPM and then dies. Fuel Pressure is 58psi. Throttle did not respond.

I did get a Po357 G code indicating a primary open, so I checked out the wiring and, just to see if maybe I had a bad coil, I switched the #3 & #7 coils and no more code. Good!

However, I then got a U0107 “Lost Communication with Throttle Actuator (TAC) Module”. I have the UBEC - C2 “power” wire plugged into the E7 position, which says, on the C2 pinout I have, it is an “ignition 1 Voltage” connection. I’m not sure I believe that. I thought I1V was a “hot on start/run” connection, but my suspicion is this is a “hot on start” (not run) connection.

Can someone briefly differentiate the terms, such as “ignition 1 Voltage”, “ignition”, etc., as far as when they’re “hot”? I’ve seen several C2 pinouts and they’re not all the same (seems possible).

Thanks …
 

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Discussion Starter · #18 ·
Back when I had the initial "No-Crank" problem, I had the PCM ground in E7. I moved it to F7 and It then would crank, my headlights started working, and it was "trying" to run.
I've been looking at the C2 pinouts for several hours and this is what I now have:

A1 - A7 - not being used
A8 - Orn Batt (pcm C1 - 20&57)
A9 - MAF
A10 - PCM (C1-19)
B3 - not being used
B4 - DBW (TAC)
B5 - not being used
B7 - Fuel Pump Relay
B8 - B9 - not being used
B10 - coil packs 1 & 2
B11 - Gry Trans Range Sw(bkup lghts)
B12 - Lt Grn Trans Range Sw (P/N Pos sw signal)
C8 - Trans (pin 11)
C10 - Injectors (6 & 8)
C12 - Stop lamp Sw (C101 (D))
D3 - D4 - not being used
D10 - Injectors (2 & 4)
D11 - PPL Starter Solenoid
D12 - not being used
E2 - Trans. Crank Voltage (pin 12 NSS) <----------not sure about this one
E8 - Trans Power (pin 1 “round connector”)
E9 - not being used
E10 - Injectors (5 & 7)
F4 - not being used
F5 - not being used
F7 - PCM Ground
F9 - H02 Sensors (both)
F10 - Injectors (1 & 3)
F11 - Trans Range Sw (pin L NSS) (Strtr Relay coil sply voltage)

These are all the terminals in my C2
I've made several changes to try to "match" up. As you all know, I'm "challenged" in this area....

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Discussion Starter · #20 ·
Just a quick one...
Does anyone have a pinout for both ends of the DBW cable from the pedal to the TAC unit? (2004 Silverado, 6.0L)
My pedal pinning doesn't exactly match the TAC end...

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Discussion Starter · #21 ·
Never mind.... I found one and everything seems to go where it should...
I have another TAC I'm going to try.

I made all the changes Harley recommended, but I still get the U0107 error and the engine runs for a few seconds and dies...
I went back and used my trusty test light to verify every thing was good A to B.

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Discussion Starter · #22 ·
This is what I now have:

A8 - Orn Batt (pcm C1 - 20&57)
A9 – Driver side coil
B4 - DBW (TAC signal)
B7 - Fuel Pump Relay
B9 – Pass. Side coil
B10 - MAF
B11 – NSS Trans (pin 10)
B12 – NSS Trans (pin 9)
C8 – NSS Trans (pin 11)
C10 - Injectors (6 & 8)
C12 - Stop lamp Sw (C101 (D))
D10 - Injectors (2 & 4)
D11 - PPL Starter Solenoid
E2 – NSS Trans (pin 12)
E7 - Ground to engine (ground wire run directly to engine block)
E10 - Injectors (5 & 7)
F7 - PCM Ground
F9 - H02 Sensors (both)
F10 - Injectors (1 & 3)
F11 – NSS Trans (pin 1)

+ Trans power (E) to C101(G) (spliced with PCM C1-75)

repeating…
checked continuity on all wires involved
tried different TAC module (no affect)
added ground wire to: Tac module, PCM, TB housing

Results are the same…. U0107 “Lost Communication with Throttle Actuator (TAC) Module”

As usual, no clue to what to try next-
 

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Discussion Starter · #24 ·
Grounds:
Battery to engine block
Battery “pigtail” to frame, with a ground strap on to the radiator support
Ground strap from the firewall ground “post” to engine
Grounds from UBEC (E7), TB base, PCM cover, to engine block
Ground spliced into PCM ground going to UBEC C2-F7, and run to engine block

Part of my problem is that I wrapped most of the harness in the cloth “tesa” type tape, to protect it from heat. So, now it’s a B*%ch to locate things. That’s my excuse anyway…

So, the problem still exists, but I appreciate the efforts on your part.



Thanks…
 

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Discussion Starter · #25 ·
Sorry, 'nuther dumb question:

How do you determine a "Hot on Crank and Run" vs. a "Hot on Run" or "Hot on Crank" circuit?

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Discussion Starter · #27 ·
On the 16 pin TAC connector there are four pins (4,5,6,14) that are Cruise Control related.
I'm not running CC, at this point, so can I just ignore these?

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Discussion Starter · #29 ·
Don't have the cruise control switch (on the turn signal stem).

More interested in just getting the damn thing to stay running (U0107 code), so I'm looking for wires that need to be hooked up.
 

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Discussion Starter · #34 ·
Can someone just tell me where this CC TAC(6) wire needs to go? The truck did not have CC originally, so there is nothing to start with, and I'm not going to hook it up right now.

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Discussion Starter · #36 ·
OK, on the C101 connector, did you connect it into pin (P) ?
If not, then I need more info. (sorry)...

Thanks for your patience with the wiring-challenged.
 

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Discussion Starter · #38 ·
If the cruise control module is separate from the TAC, then No, all I have is the TAC, it's pedal to TAC and TB to TAC connections. I have the four CC wires, but none are connected at this time, and the truck did not have CC, so there is nothing to connect them to.

Thanks...
 
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