no power 2003 tahoe

having accelaeration problems with stalling codes p0120&p0220

Check for poor grounds at the back of each cylinder head.

You may need a new throttle body.

thank you for your reply i will check that ive been an import technician for several years this is just an odd problem because somtimes the dang thing will run perfect and everything ive ohmed out seems to be within in specs

OK since your a tech I can give you a more in depth diagnosis procedure.


1. Check pin terminal connections at the plug to the throttle assembly underhood.

2. Probe a voltmeter to the Dark Green wire at the Throttle Position Sensor (TPS) and monitor for a glitch in the signal voltage.

3. Inspect the Yellow Throttle Actuator Control (TAC) motor control circuit #581 about 1 inch to 4 inches from the throttle body connector to see if it is broken inside of the insulation. (There is a tsb on this)

if the code is cleared and doesn't come back right away it could be an intermittent problem. That being said, if it is intermittent, all the resistances may check out normal. you should drive it with a graphing scanner hooked up and hopefully while you are driving the problem pops up and you can look at the graph to see what signal to check out. There is a TSB about the wire harness connector having breaks inside the insulation and there are some that say it could go back as far as ten inches from the connector.