Dhmoto111

iTrader: (1)

i have a few problems here
im just now getting the 5.3L going in the scout...(out of an 01 tahoe)

to start i am throwing a p1518 code(electronic throttle module to pcm comunication)
All the wires are excactly like they are supposed to be and have continuity on each wire from connector to connector but no throttle response

TAC pin 12 connects to pin 14 C1 on the PCM
and TAC pin 13 to PCM pin 15 C1
both of those wires are good

the TAC module has power at pin 7
as i was writing this i thought about checking the continuity to ground at pin 15 and it has 20 ohms that shouldnt be...right?? edit: with the connector unpluged from the connector to ground key on 20ohms key off 0 ohms (IIRC in the schematic it shows that it goes straight to ground so ill have to check that out)
the 2 5v references at pin 2 and 9 both have 5volts
tp sensor 1 signal (pin 1) has 1v at closed throttle and 4.7v at open
tp sensor 2 signal (pin 11) has 3.9v closed and .2v open
the accelerator position sensor has all the 5v ref. and various signal voltages
TAC motor has battery voltage on both wires while unhooked

from what i can tell everything is working as it should (ecept maybe the ground as i just realized) yet its apparently not comunicating to the PCM

at first i would try to start it and it would just die right away then i unhooked the MAF and now it will idle up smooth to about 1500 rpm i would guess, then sometimes slower than others idle down to what i would imagine to be about 400-500 rpm and just BARELY runs

maybe a bit of important info. on the initial start up i had the TAC module sitting on the valve cover while i was doing some wiring. anyway i forgot about it and left it there so after i started it (fired up, ran normal and i shut it off after maybe only a second or 2 just to make sure it would start) so i went back to the engine bay and noticed that it had fallen and was now hanging against a plug wire right at the coil. didnt think to much about it at the time (before i knew there was a problem) but could it be that a spark voltage was induced to the module? possibly knocking something out along the lines of serial data communication between the TAC and PCM



also in the HPtuner Scanner mode the only indication of sensor data i get while running or not is battery voltage nothing else at all no RPM, MAP, TPS, 02's... or anything

the editor works fine i can edit info and what not and comunicate to the PCM
Im not sure if that is related or not

If i wanted to use a cable actuated throttle body would i need to flash the PCM to something like an 01 Fbody i briefly looked over and compared the pin outs and for the most part they are the same

so i would guess i just need to hook up the TPS and IAC to the the pcm or would it not be that simple?


thanks in advance for any help you can offer.

Dhmoto111

iTrader: (1)

well i went ahead and got another tac module because im running out of time fast


would no tps signal cause it to idle so poorly like that? it makes sense to me. the throttle blade just stays slightly open causing it to idle high smooth and then back down really low and rough. since there is no IAC valve...

i hope it fixes it

69MyWay

iTrader: (2)

I realize I am reviving a very old thread here - how did you solve the problem?