po121 and 122
Thread Starter
Staging Lane
Joined: Oct 2002
Posts: 59
Likes: 0
From: houston
po121 and 122 121 122 have those codes that keep showing up. I replaced the tp sensor and it still gets those codes. The car shifts into OD way to soon and wont down shift out of OD sometimes. Anyone ever have this problem or know what to look for to fix it?
On The Tree
Joined: May 2003
Posts: 106
Likes: 1
From: Apache Junc, Az
Re: po121 and 122 P0121 sets when the predicted throttle angle does not match the actual throttle angle.
P0122 sets when the TP sensor signal voltage is less than 0.2 volts.
It sounds like you have a wiring problem ( broken wire somewhere). You can count on this low voltage being lower than normal closed throttle voltage. A bad ground would increase sensor output so rule that out. It is possible that your 5 volt reference voltage took a dive so carefully inspect the wiring to the sensor. To save weight, the wiring is smaller and is more prone to breaking inside the insulation. The telltale signs of internal breakage would be a bubble in the wiring insulation. You could also have had a loss of 5 volt reference from the PCM. If so, you would expect DTCs from other sensors using the same 5 volt reference. Usually this is an EGR DTC.
P0122 sets when the TP sensor signal voltage is less than 0.2 volts.
It sounds like you have a wiring problem ( broken wire somewhere). You can count on this low voltage being lower than normal closed throttle voltage. A bad ground would increase sensor output so rule that out. It is possible that your 5 volt reference voltage took a dive so carefully inspect the wiring to the sensor. To save weight, the wiring is smaller and is more prone to breaking inside the insulation. The telltale signs of internal breakage would be a bubble in the wiring insulation. You could also have had a loss of 5 volt reference from the PCM. If so, you would expect DTCs from other sensors using the same 5 volt reference. Usually this is an EGR DTC.
Moderator
Joined: Nov 2001
Posts: 3,048
Likes: 12
From: Raleigh, NC
Re: po121 and 122 Looks like we posted almost the same time:
HELP! Short-Shifting out the hole - any ideas?
https://ls1tech.com/threads/showflat...31&fpart=1
HELP! Short-Shifting out the hole - any ideas?
https://ls1tech.com/threads/showflat...31&fpart=1
Thread Starter
Staging Lane
Joined: Oct 2002
Posts: 59
Likes: 0
From: houston
Re: po121 and 122 okay a break in the wire i can fix. I think it may be more than one wire thats broken cause sometimes it shifts hard as hell when i put it in drive. so that would be the ground. any one know what pin # the 3 wires go back to. i will run a new line
Thread Starter
Staging Lane
Joined: Oct 2002
Posts: 59
Likes: 0
From: houston
Re: po121 and 122 i re-wired all 3 wires back to pcm and still not working right. when it shifts to soon i can put it to the floor and it wont down shift and autotap shows 100% for TP. Dont know if its the tranny or the pcm that messed up but i know its not the tps or wires going to it cause autotap shows it working fine.
Teching In
Joined: Jun 2003
Posts: 18
Likes: 0
Re: po121 and 122 I am having the exact same problem. I am hoping it is due to me moving the tb screw. I am going to check tonight with a voltmeter to see if the setting at closed is 0.6v and at full throttle is 4.65v. I will let you know if that fixes it.
Trending Topics
Teching In
Joined: Jun 2003
Posts: 18
Likes: 0
Re: po121 and 122 Well, I checked my settings and at closed throttle it was at .8 and WOT it was at 4.35. I have adjusted the screw so that it is now reading .62 and WOT is still 4.35, but autotap shows that as 100% throttle. I have reset the pcm and the DTC has not shown back up yet.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
10 Reasons the LS7 Is GM's Most Extreme Naturally Aspirated V8 Engine Ever
Verdad Gallardo
Teching In
Joined: Jun 2003
Posts: 18
Likes: 0
Re: po121 and 122 Here's what I did exactly
Bought a multimeter, set it to the 0-20vdc setting. Next turned my ignition to the on position. Punctured the blue wire going to the TPS with a sewing needle. Placed the positive lead from the multimeter on the sewing needle and the negative lead on the bolt for the strut tower brace. The reading was 0.8v Next I turned the idle screw down until it was at 0.62. Then I opened the throttle body all the way and it read 4.35. I had it autotaped from a friend later in the week and it showed that it was at 0% throttle closed (0.62v according to multimeter) and 100% (4.35v).
I hope this fixes it for you
Bought a multimeter, set it to the 0-20vdc setting. Next turned my ignition to the on position. Punctured the blue wire going to the TPS with a sewing needle. Placed the positive lead from the multimeter on the sewing needle and the negative lead on the bolt for the strut tower brace. The reading was 0.8v Next I turned the idle screw down until it was at 0.62. Then I opened the throttle body all the way and it read 4.35. I had it autotaped from a friend later in the week and it showed that it was at 0% throttle closed (0.62v according to multimeter) and 100% (4.35v).
I hope this fixes it for you
