i have a 2nd hand 2000 4x4 light truck 1/2 ton silverado with approximately 21k miles on it.

firstly my MIL indicated service 4x4 and saw a blown atc fuse. replaced it and still keeps on blowing. checked and cleaned all the grounds and the 4x4 switch, now its doing fine except for a new problem, DTC P1875.

Sometimes when i start the truck there's a series of clicks (like a relay) coming near the 4x4 switch. Also, some othertimes the transmission shifts differently like jumping gears.

Replaced all the fluids and filters but still the same.

Did the DIY P1875 explained but stopped on the diagnostic chart part 1 of 2 step #2 because it said yes and go to diagnostic aids.

Does this mean that it's not my tccm thats bad? probably poor grounding or bad wiring? or maybe we checked it during the time when it wasn't showing problems (my erratic shifting is intermittent)?

one more thing, where can i find the vcm. GM guys here 'thinks' its the pcm.

any help from you guys is highly appreciated.

 

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First diagnose and clear any engine DTCs or TP sensor codes that are present. Then inspect for any transmission DTCs that may have reset.[/align][align=left]



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Inspect the connectors at the PCM, the Transfer Case Control Module/Transfer Case Switch and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.[/align][align=left]



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Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Wiring Systems.[/align][align=left]



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Low pump pressure and a slipping trans can cause DTCP1875 to set.[/align]It sounds like you have an intermittent short to ground in the wiring.

[ol]Install a Scan Tool .
Turn ON the ignition, with the engine OFF.
Important:Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM.
Record the Freeze Frame and Failure Records.
Clear the DTCs.
Place the transmission in NEUTRAL.
Select 4WD, then 4WD Low on the transfer case selector lever. [/ol]
Does the 4WD Low on the scan tool display Disabled when 4WD is selected, then Enabled when 4WD Low is selected?

If you have done these tests and it say go to Diagnostic aids, then the PCM, Transfer case shift control module and Pcm are probably ok.

The PCM is located near the left front inside the engine compartment. There is no VCM.

 

thanks for the reply.

tried the links:

Testing for Intermittent Conditions and Poor Connections
Testing for Electrical Intermittents

but it says that i'm not authorized.

you said that the pcm and transfer case shift control modules are probably ok. how about the transfercase control module? do you think this is ok too?

i think you're right i also think that probably it's a short or a loose connection coz of my previous problems of atc fuse blowing and one instance of fuse for the fuel being busted.