need help with 03 tb

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need help with 03 tb

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Chevrolet Forums >> Chevy Trucks, Vans & SUV's >> Trailblazer >> need help with 03 tb

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need help with 03 tb - 9/2/2008 11:20:53 AM

asumner05

Posts: 1
Joined: 9/2/2008
Status: offline

I am new to this but i have tried to look before i posted. I have codes p1221, p1271 and p1481. The reduced engine power light, check engine light, the traction control light and the gas gauge jump up and down. can someone please steer me in the right direction of where to start with these codes? thank you

_____________________________

a.w. sumner

Post #: 1

RE: need help with 03 tb - 9/2/2008 1:41:26 PM

rbarrios

Posts: 249
Joined: 2/1/2007
Status: offline

P1221 = Fuel Pump Secondary Circuit Low (hope it''s not failing)P1271 = Accelerator Pedal Position (APP) Sensor 1-2 Correlation
and P1685...
GM Bulletin for this combination of codes:

Quote:

1.Inspect the main engine wiring harness between the PCM and the Generator Assembly for a potential short to ground. There is a metal wiring harness retainer in this area that secures the main engine harness. If the harness conduit is mis-positioned, some of the wiring may become exposed and chaff on the harness retainer. This may eventually cause the exposed circuit to short to ground. 2.Inspect the 3 harnesses that connect to the PCM for potential shorts to ground on the metal PCM mounting bracket, just below the PCM. There are plastic harness retainers on the PCM bracket that secure the harnesses to the PCM bracket. If the harness conduit is mis-positioned, some of the wiring may become exposed and chaff on the PCM bracket. This may eventually cause the exposed circuit to short to ground. 3.If a chaffed circuit is found in either of the locations above, repair the circuit (s) using the necessary SI procedures. Once the circuit is repaired, tape the area of the affected area of the harness to prevent the wires from becoming exposed in the future and secure the harness using the original harness retainer. If Service Information diagnostics continue to lead to PCM replacement even though it was recently replaced for the same concern, the PCM may have internal damage due to a shorted driver circuit or low reference circuit. It also mentions a possibility of the fuel level sensor low reference circuit being shorted inside the fuel pump module.

If none of the above quoted failures are found, a Tech 2 is really needed to ensure proper operation of all the PCM drivers...leading you to the circuit in which the short is present

in your case. The PCM will set P1481 if it detects a loss of the cooling fan speed signal for more than 11 seconds. It will then command the fan clutch to 100%, and will light the MIL if the signal fails during a second consecutive ignition cycle.There are three circuits between the PCM and the fan which support the cooling fan speed signal:DESC.; COLOR; Pin at FAN; PCM; C1055v REF; GRY; E; WHT-60; ASignal; DK BLU; D; BLU-43; BGND REF; GRY or GRY/WHT; C; BLU-60; CC105 is the 10-way I/P-to-Forward lamp harness inline connection, located near the underhood fuse block.

(in reply to asumner05)

Post #: 2