P1221 Code - Need some opinions
Thread Starter
Drifting
Joined: Dec 1999
Posts: 1,541
Likes: 2
From: Raleigh NC
P1221 Code - Need some opinions
Disregard!!! It ended up being the ls6 to ls2 wire harness. The blue wire wasn't making good contact
2003 Z06 with a Fast 90 and LS2 90MM throttle body with harness adapter.
History: I've mod'ed the car quite a bit. At one time I had the factory LS6 with a maggie. With the maggie I had to splice in an extension for the TB harness. Never had an issue with it. When I removed the maggie I removed the extension and was left with a decent soldered joint. Never had any issues until recently. The motor now is an after market ls3 stroker with fast and 90mm throttle body. The throttle body was ported by one of the "expert" internet porters. It has worked flawlessly for at least 4 years.
To the present: About six weeks ago I had the 1120/1221 pop up with the reduced power message. First thing I did was examine my splice. Checked it out and taped it back up and it was fine.
Last week I had to pull my drivers side header (Kooks 1 7/8)out to have the air tube welded back on. You have to jack then engine up to remove and to make life easier and to provide more clearance I took the intake off. After I got everything back together I had the the P1120/1221 codes. If I try to start it I will get a 1220 and 1516 as well. From what I understand trying to follow the manual I tried to address the 1221. I followed the procedure the best I can without a scan tool. The two 5 volt signals come in at 4.98 and the wire harness checks out for cross shorts and continuity. The only thing that I did notice is that the blue wire (TP1 signal) has a constant 5 volts even if I disconnect the harness from the throttle body. When I moved the throttle blade the TP2 signal value changed correctly but the TP1 signal stayed at a constant 5 volt. I checked for continuity between the TP1 signal terminal on the TAC to all other terminals and it came up clean.
I'm thinking I need a new TAC module. My wife has an 08 so if I can talk her into it I will borrow her throttle body to see if the codes clear.
Opinions?
2003 Z06 with a Fast 90 and LS2 90MM throttle body with harness adapter.
History: I've mod'ed the car quite a bit. At one time I had the factory LS6 with a maggie. With the maggie I had to splice in an extension for the TB harness. Never had an issue with it. When I removed the maggie I removed the extension and was left with a decent soldered joint. Never had any issues until recently. The motor now is an after market ls3 stroker with fast and 90mm throttle body. The throttle body was ported by one of the "expert" internet porters. It has worked flawlessly for at least 4 years.
To the present: About six weeks ago I had the 1120/1221 pop up with the reduced power message. First thing I did was examine my splice. Checked it out and taped it back up and it was fine.
Last week I had to pull my drivers side header (Kooks 1 7/8)out to have the air tube welded back on. You have to jack then engine up to remove and to make life easier and to provide more clearance I took the intake off. After I got everything back together I had the the P1120/1221 codes. If I try to start it I will get a 1220 and 1516 as well. From what I understand trying to follow the manual I tried to address the 1221. I followed the procedure the best I can without a scan tool. The two 5 volt signals come in at 4.98 and the wire harness checks out for cross shorts and continuity. The only thing that I did notice is that the blue wire (TP1 signal) has a constant 5 volts even if I disconnect the harness from the throttle body. When I moved the throttle blade the TP2 signal value changed correctly but the TP1 signal stayed at a constant 5 volt. I checked for continuity between the TP1 signal terminal on the TAC to all other terminals and it came up clean.
I'm thinking I need a new TAC module. My wife has an 08 so if I can talk her into it I will borrow her throttle body to see if the codes clear.
Opinions?
Last edited by Rob's 73; Nov 20, 2010 at 01:40 PM.
Thread Starter
Drifting
Joined: Dec 1999
Posts: 1,541
Likes: 2
From: Raleigh NC
Morning update
Borrowed the throttle body from my wifes car. Same codes. So that eliminates the throttle position sensor. How much does a new TAC module cost? I can't find it on Gene's website.
