Good afternoon.
The U0121 is a serial data fault. This system sends a signal to all the modules for the operation of all the modules.
The 597 is for a failed PCM.
The 852 is also referring to the PCM and is a transmission code.
You will need an advanced scan tool to monitor the systems to help determine the failure.
Roy
P0852
Descriptor
Probable Causes
Control Solenoid Valve Assembly
Engine Control Module (ECM)
Transmission Internal Mode Switch (IMS)
597
P0597
Descriptor
Probable Causes
Engine Control Module (ECM)
Engine Coolant Thermostat Heater
u0121
Recommendation/Instructions
When diagnosing an intermittent electrical concern, terminal tension is one of the main culprits, especially when working with very small terminals. More and more modules and inline connectors are using small.64 series terminals and when checking terminal tension it is important to use the correct test probe. The J-35616-64B is the latest test probe released for checking tension or probing the.64 series terminals. See pic below.
Note: Always refer to the Connector End View in Service Information for the latest information on determining the correct test probe to use.
If the terminal end of the J-35616-64B is bent, damaged, worn or broken it should not be used and a replacement test probe or terminal should be obtained from GM Tools at 1-800-468-6657. The test probe terminal has been released in the terminal repair kit (J-38125-620H) located in Lear Tray 7 part number 963716-2, shown below (Note: When calling Kent-Moore to order terminal 963716-2, the actual part number is 963716-2PKG since they are only sold as a pack). This terminal may also be used to make jumper wires; example: to jumper the High Speed LAN circuits together in order to bypass a module for testing only. Use crimping tool J-38125-641 and jaw "H" for 22ga wire, "J" for 20 ga wire, or "K" for 18 ga.
If you cannot locate the Terminals in your terminal kit "Tray 7, " your kit is not up to date, and Kent tools will need to be contacted so your kit can be updated.
Another option is to order the.64 test probe terminal already connected to a lead/wire called a terminated lead. The GM part number is 13505346, which can be ordered through your normal GM CCA parts channel. There are 5 terminated leads in a package, shown below. With the addition of this new terminated lead, there are now 3 different options for obtaining the proper.64 test probe/terminal:
.64 Test Probe - J-35616-64B (ordered from GM Tools at 1-800-468-6657)
.64 Replacement Terminal - Lear Tray 7 part number 963716-2 (ordered from GM Tools at 1-800-468-6657)
64 Terminated Lead - GM part number 13505346 (ordered from GM CCA parts)
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Friday, August 9th, 2019 AT 12:44 PM
