Reduced power mode

From Jacobandnickolas
Apr 23, 2014.

U0107 can set if the battery voltage is low. Check to make sure that isn't an issue. Also.
It can also set if there is a short to B+ on the TAC module ground circuit. Check fuses for the circuits that are in the TAC module harness. Finally, this code can also be set if the TAC module ignition feed circuit is shorted to a B+ supply circuit. When the ignition switch is turned on, the TAC module is powered-up before the PCM. The code sets because no communication is detected by the TAC module from the PCM. You will need to check circuits for being shorted to a B+ supply.

Scan for codes first it may say what area to check

Sorry my goof id didn't read that part in header. Low voltage causes this so check battery for condition including load test as well as dirty terminal ends on battery. Also check belt and tensioner as it may be slipping recommended replacement is 60 k for both. Finally cleant throttle plate on both sides and iac hole with choke cleaner. If battery is disconnected you may need to reset anti theft. If it continues a pro will have to check this to see If the calculation is correct between actual throttle position as well as calculated position because that is what this code is.

You may have one or two problems here, try removing Ground G103 on the back of the cylinder head, clean both the mating surface and the wire end, use emory cloth and get it nice and brite, re attach ground and cover with RTV. Let me know if this helps, here's the GM TSB on it:
CHECK ENGINE LIGHT ON WITH NO DRIVEABILITY CONCERNS, DTC P0120, P0220, P1516, P1518 (CLEAR CODE) TECHNICAL SERVICE BULLETIN Reference Number(s): 03-06-04-032, Â Date of Issue: Â June 16, 2003 Related Ref Number(s): 03-06-04-032 ARTICLE BEGINNING CONDITION Some owners may comment that the Check Engine Light is illuminated and there is no driveability concern. Upon investigation, the technician may find codes P0120, P0220, P1516 or P1518. Also, technicians may note that low voltage codes P0562, P0563, P1637 or P1638 have been set. CAUSE The Tach module may set the code in error if it operates at a battery voltage of 4.5 to 5.0 volts. CORRECTION If the vehicle has stored one of the low voltage codes, P0562, P0563, P1637 or P1638, follow the appropriate diagnostics for the low voltage code. In most cases, this will lead to correcting the concern without replacing any Electronic Throttle Control (ETC) components. If codes P0120, P0220, P1516 or P1518 are present without any of the low voltage codes, the technician should observe the Engine RPM in the fault record. Ã Â Â If the Engine RPM in the fault record is zero and the customer indicates that the vehicles has experienced a low voltage condition, the code should be cleared and the low voltage should be diagnosed and corrected. Ã Â Â If the Engine RPM is zero and the customer indicates that there have been no low voltage conditions, then the P1516 diagnostic aids for intermittent concerns should be used to diagnose and correct the vehicle. Ã Â Â If the Engine RPM is greater than zero, then check for an obvious loose ground at G103 located next to the right cylinder head just below the head and mounted into the block. Also, check G104 located behind the left cylinder head. Then verify all electrical connections at the TAC module. If the concern is still not resolved, contact Technical Assistance. CADILLAC: 2003 Escalade, Escalade EXT, Escalade ESV with 4.8L, 5.3L or 6.0L Engine (VINs T, N, U - RPOs LM7, LQ9, LQ4) CHEVROLET: 2003 Avalanche, Silverado, Suburban, Tahoe with 4.8L, 5.3L or 6.0L Engine (VINs V, P, T, Z, N, U - RPOs LR4, LM4, LM7, L59, LQ9, LQ4) GMC: 2003 Sierra, Yukon, Yukon XL with 4.8L, 5.3L or 6.0L Engine (VINs V, P, T, Z, N, U - RPOs LR4, LM4, LM7, L59, LQ9, LQ4) SECTION: 06 - Engine/Propulsion System

I was asked to assist-check all wiring connections on the PCM if okay have the PCM tested or get it flashed and see what happens-you got too many codes could be one and throwing off the others

You can try testing the throttle position sensor and manifold absolute pressure sensor

I had a major 2 drive computer crash, wish I could pick these pieces up like I can with cars. Sorry, to further help I need the engine size in liters, 1500 HD?
Diagnise the P0758 code, and check with Chevy on these others, this group of codes is for several problems, but is supposed to be harness and or ground related. Did you check for ground strap and battery negative connection to the block as well, Might be worth a shot.
P0758= Short to ground or open in + in the 2-3 shift solenoid circuit, so check the wiring harness at the transmission for a good connection and for water intrusion in the connector.
Thanks for the help Jess, I was completely down for a few days, slowley getting off the mat!
Reinstalling all my gear.

I would start by getting it scanned at a chevy or gmc dealer, although it will cost money, they can read the ignition switch actual and read positions, this sounds like an ignition switch issue.