Silverado code t1516

[pmarc]

re: silverado truck 1500 2003 engine: LM7
fault code: T1516 TAC MODULE [engine indicator light has been on for 2 years]

1. 3 days ago hard start; progressing to no start yesterday

2. AAA jump started it and I drove off, but only at 10 mph - truck couldn't go faster. depressing accelerator did not result in change in speed nor a rev'ing sound

3. the AAA guy tested battery and alternator concluding neither was bad

4. truck in shop now and they want $500 to replace battery, belts, tensioner, with no guarantee it will be fixed

QUESTION: THE FAULT CODE T1516 WILL NOW GUIDE THE TECH AWAY FROM THE BATTERY, BELTS AND OTHER ERRONEOUS AREAS.

THE SHOP IS AWAITING MY NEXT MOVE. T1516 IS A BIG "PLACE" TO DO RESEARCH. WHAT DO I TELL THEM NEXT? IS THERE AN INCREMENTAL APPROACH, FOR EXAMPLE? WHAT WOULD YOU DO?

[j cAT]

Originally Posted by pmarc

re: silverado truck 1500 2003 engine: LM7
fault code: T1516 TAC MODULE [engine indicator light has been on for 2 years]

1. 3 days ago hard start; progressing to no start yesterday

2. AAA jump started it and I drove off, but only at 10 mph - truck couldn't go faster. depressing accelerator did not result in change in speed nor a rev'ing sound

3. the AAA guy tested battery and alternator concluding neither was bad

4. truck in shop now and they want $500 to replace battery, belts, tensioner, with no guarantee it will be fixed

QUESTION: THE FAULT CODE T1516 WILL NOW GUIDE THE TECH AWAY FROM THE BATTERY, BELTS AND OTHER ERRONEOUS AREAS.

THE SHOP IS AWAITING MY NEXT MOVE. T1516 IS A BIG "PLACE" TO DO RESEARCH. WHAT DO I TELL THEM NEXT? IS THERE AN INCREMENTAL APPROACH, FOR EXAMPLE? WHAT WOULD YOU DO?

check fuel pressures could be fuel pump...
why would they mess with the electrical system ...if its got the correct voltages !

dtc 1516 is the throttle position actuator control..this is a common problem as the connector at this throttle control gets corroded...then with the pcm seeing this puts you in crawl mode very slow speed ...this is a saftey designed into the computer when the signal is bad..

[pmarc]

why would they mess with the electrical system ...if its got the correct voltages !

***I figure they know this. [Still pays to sell a battery while they're at it; although they're loosing a customer's faith in them at the same time]. Anyway, thanx. I didn't know this code was so potentially specific to the problem.

By the way, can you help me know how the hard starts are related to 1516? There was a warning as start problem evolved over 3 days. On day 3 minimal or no power was available - to anything, incl the disc player and motorized driver's seat.

[j cAT]

Originally Posted by pmarc

why would they mess with the electrical system ...if its got the correct voltages !

***I figure they know this. [Still pays to sell a battery while they're at it; although they're loosing a customer's faith in them at the same time]. Anyway, thanx. I didn't know this code was so potentially specific to the problem.

By the way, can you help me know how the hard starts are related to 1516? There was a warning as start problem evolved over 3 days. On day 3 minimal or no power was available - to anything, incl the disc player and motorized driver's seat.

with the low voltage to the electrical system you may have a bad electrical system/shorted [internal] battery...

with low voltages all kinds of weird things happen...

testing is required ..before installing parts..

the dtc 1516 is something to correct after the electrical system is working.never assume they know about TSB that GM sends out to dealerships only !

[pmarc]

so I should have them check for voltage leaks first?

is there a difference between [internal] battery and the one I always see mounted on top with 2 cables?

[j cAT]

Originally Posted by pmarc

so I should have them check for voltage leaks first?

is there a difference between [internal] battery and the one I always see mounted on top with 2 cables?

no , the battery internally has plates these plates can short out then the low voltages...this can be very intermittent...this is the internal short I am talking about ...replacing the battery sounds good to me. save old one ..put charger on it this will usually reveal if the battery is n/g

[pmarc]

The tech says only 11V coming out of battery. He's positive it's shorted. So we'll switch the battery and see what happens. He already checked the wires on the tac - no problem.

[j cAT]

Originally Posted by pmarc

The tech says only 11V coming out of battery. He's positive it's shorted. So we'll switch the battery and see what happens. He already checked the wires on the tac - no problem.

I had a vehicle where the owner was told he needed an alternator.I found that it was the battery shorted causing the alternator to show failure..put charger on battery and the current needle pegged out max..

10.5 volts means 1 cell is bad..should have 12.5 volts when fully charged.

[pmarc]

good to know. i just hope they dont force me to buy the tensioner and belts -- $347