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was dealing with a no start this morning.
pulled codes TAC.
replaced.
truck starts, throttle wont work, has high idle.
now getting TPS fault signal. replaced the tps last time and the throttle worked, looks like something caused it to go bad again during the whole issue search.
DBW is about the dumbest damn idea, I know you say it helped the cars w/t traction control or whatever...bah...:)
Post DTC's please.
I dont have them. they were the same codes from the last run around.
if the sensor doesnt fix it, which it did last time, then he will post the new codes.
Well TAC and new TPS didnt fix the problem
truck will start. throttle body butterfly will not budge. it worked last week with key on, engine NOT running but hasnt worked since the truck fired up, now it wont work with the key in run, engine NOT running.
idles way too high though, probably expected given the codes.
codes are as follows:
P0120
P0220
P1516
P1518
If anyone has the info on what points and how much of whatever should be tested on the sensors, Id appreciate the info, diagram wouldnt hurt, as I think there are 16 or so wires on the TPS.
With electronic components you have to be careful what you try to measure with a meter. Sometimes simply testing the wrong leads will fry an internal circuit. Don't just go hap-hadzardly probing things if you're not for sure what to check and where.
From memory those look like two for the TPS (one for each) and two for the TAC motor. I've yet to see a TAC blade open by pressing the pedal key on engine off but I guess it's possible. The idle speed is set in the PCM. It's probably high as a result of the DTC's you have (default). All of the problems you describe are symptoms of the DTC's. Find the cause of the DTC's and the other stuff will be cured.
Let's see what the manual says...
If the PCM detects one or more of the TP sensor 1 tests are out of range, DTC P0120 sets:
1) The TP sensor 1 signal circuit voltage out of range
2) Throttle blade min position for TP sensor 1 out of range
3) 5-volt reference of the TP sensor 1 tests out of range
Same for P0220 except related to TP 2.
DTC P1516 sets if the PCM detects an out of range condition between the predicted and the actual throttle position.
P1518 is the kicker and probably the source of the trouble.
The throttle actuator control (TAC) module and the powertrain control module (PCM) communicate via a dedicated serial data circuit. This serial data circuit is separate from any other serial data circuit on the vehicle. Accurate transmitting and receiving of serial data requires not only good circuit integrity, but also adequate system voltage. This diagnostic test monitors the accuracy of the serial data transmitted between the TAC module and the PCM. Make sure the power and ground sources to the TACM are good and the communication circuit between the PCM and TACM is good end to end.
This DTC gets a lot of folks. It can even be stored because of a weak or undercharged battery. Why? Because if the PCM and TACM "wake up" during key on at slightly different times due to low battery voltage, the DTC sets and you get reduced engine power (on a newer application with a DIC in the IPC). Make sure the battery is good and strong.
BTW, the 5-volt references for the TPS's come from the TACM so if it's out to lunch, not powered, or not grounded, you'll have the two TPS DTC's above.
yepQuote:
Originally Posted by RedHeartbeat
gassguzzler
so you think it has to do with the TAC module.
how would one test the tac module? there are a few wires to and from, so a diagram would be great.
this thing flat wouldnt start, so he put in a TAC module, it idles now but the throttle blade wont move, hes been getting the modules at the junkyard, the sensor is new, could it be the tac is just programmed wrong for his year/tb or whatever the reason?
so you say engine not running the throttle blade shouldnt move? last week, key to run (engine not running) that sucker moved.
thatll work
thanks
I have a question now.
That schematic shows 15 wires.
There are 16, there is a pink one.
With key on, engine NOT running.
Only sign of power was the pink wire, which is 12v switched to the TACM. There was no sign of power (5V) at the pedal or out the TACM.
he then tested the low reference for ground, key on and off. Brown was a ground. purple and gray did not show to be a ground, although they are. tan shown to be a ground with key on, which is odd, as its 5v reference.
This sounds alot like the issue we just had with a bad ground but the wires are through the pcm I believe so....
Do you think this its the module? This one isnt cheap.
I wasnt clear on the inlet wires, as far as, which ones would be grounds? Im guessing pink the the power source, unless there is supposed to be a 12v constant im not aware of.
In any case, key on, the pink was the only source of power.