SOLVED! Locked in Park, Won't activate starter (or click)...?

Roamingdoc

Original poster
Member
Dec 23, 2012
34
Prescott, AZ
I think so. The failure to start (which, coupled with no crank, cannot shift out of park, but most dash elecs and windows, lights) was the first and that was "after" the 'blown rear diff', which lead to the discovery of the damaged or malfunctioning transfer case and that to the bad transmission (all replaced with remans or 'used but warrantied' [a little]). So since that left out overnight in the wet failure and the mechanics two day (minimal cost, work on when could, pity?) mentioned of pin drag and pressure on the fuse box and so forth it has not failed to start. HOWEVER just three days ago, and for the first attempt since all the transfer case, tranny, and rear end repairs "I" put the electric selector into Alwheel and the "service 4 wheel drive" light came on (I am getting my code reader out today) and the selector would not revert back to 2Hi (would turn back to that but no light behind it) .. UNTIL I shut the car off and turned it back on a few minutes later. So Leaving out the HVAC which vent clicking noise that I've had for a year and haven't fixed we are HEADING back to the mechanic to try all the transfer case selections in his large repair location so just in case.... no towing needed. Darn. I am getting annoyed at the TBlzer.
 

mrrsm

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Oct 22, 2015
7,639
Tampa Bay Area
If your Code Reader is sophisticated enough to read "B" DTCs and the DTC# B -2725 shows up... Check out THIS TSB Information for 2002 Chevrolet Trailblazers and GMC Envoys presenting with this "Service 4WD" Indicator condition... or bring this Topic up in conversation with your Mechanic to find out if THEY took any of these actions:

Service 4WD Indicator Illuminated, DTC B2725 Set (Replace Transfer Case Shift Control Switch)

#02-04-21-002

"Service 4WD" Indicator Illuminated, DTC B2725 Set (Replace Transfer Case Shift Control Switch)

2002 Chevrolet and GMC S/T Utility Models (Trailblazer, Envoy) with Four Wheel Drive

Condition
Some owners may comment on the Service 4WD Indicator illuminating. Upon investigation, the technician may find a DTC B2725.

Cause
The condition may be due to the transfer case shift control switch.

Correction
Replace the transfer case shift control switch using published Service Information procedures. Verify that the vehicle contains the latest calibration for the automatic transfer case control module. Calibrations are electronic calibrations and are NOT available from GMSPO. Calibrations will be available from Techline starting January 2002, on the TIS 2000 version TIS 01/2002 data update or later. Reprogram the automatic transfer case control module if necessary.

Parts Information
Part Number Description Qty
15097405 Transfer Case Shift Control Switch 1

Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Description Labor Time
K4123 Switch, Transfer Case Select - Replace Use Published Labor Time
J6355 Prom - Reprogramming (as necessary) Use Published Labor Time


Naturally, Your preference for ANY Replacement Component should ALWAYS be for the OEM GM or ACDelco Parts available via GMpartsdirect.com or from RockAuto.com... but keep THIS one in mind from Amazon ** jik*** the others are not available:


WVEAWDSWITCH.jpg61-mVP7ZRcL._AC_SL1500_.jpg619w3EucW6L._AC_SL1500_.jpg61DEB-7Xz3L._AC_SL1500_.jpg71nhRbGsqDL._AC_SL1500_.jpg618WgbtEEqL._AC_SL1500_.jpg
 
Last edited:

Roamingdoc

Original poster
Member
Dec 23, 2012
34
Prescott, AZ
The code showed (on a more advanced reader than I have) a C0327 and it showed on a graph the activation of that "old" (read: original) transfer case shift motor... I decided to replace it as, while the replacement transfer case was much newer, this was the old (326K) weak link... Napa has a good warranty, the Chevy dealership wanted my left nut but the place I go to diagnosed it, discussed it, ran several more tests (free) and said, think we can get the napa part and have it end of day tomorrow (today) ... I suppose at one time I could have crawled under and done it but those days are fast becoming 'gone'... hhaha. I was really interested in the code reader... I DO NOT know much about those beyond my little inexpensive one that gives a number and then can clear it. The one at the Summit shop was actually "apparently" monitoring the function of the part/elec and graphed it, showing a glitch, etc... was a Snap On part and probably pricey but fun. WHAT the car was doing was: Start in normal 2Hi... rotate the selector (and I was in neutral not moving) to 4Hi and the 'service 4 wheel drive' light came on (and NEVER went off) but the car 'was' in 4Hi... however it would not shift back to 2Hi or any other selection... and reverse in 4Hi was VERY tight (I mean is that normal, had to give it a good amount of gas, about 1200 rpms, to get it to roll back?) Anyway I did all this at the shop so we didn't get stuck somewhere and the mechanic who works on it (there are a good half dozen at this location) has asked to work on our TBlzer, says it is a good "test of his knowledge", hahhahah. WE had changed the selector previously but the code seemed to indicate the actual shift motor?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
A good diagnostician with a good scanner would be able to pinpoint the failure by watching the data as the TC was shifting. Sounds like the motor itself is working since the drivetrain was bound up and probably crowhopping when turning while moving on pavement. However, the sensor within the motor is probably not reporting its position properly back to the TCCM. This can be confirmed via the scan tool. The new motor will likely fix it unless it's a wiring issue which should be confirmed first by doing continuity tests between the motor connector and the TCCM.
 

mrrsm

Lifetime VIP Donor
Supporting Donor
Member
Oct 22, 2015
7,639
Tampa Bay Area
In an echo of another recent Post where @Mooseman highlighted this very idea that a "Good Diagnostician using Good Tactics... with a Good Scan Tool..." can show up most Dealerships, here is another "Spot On Example".

In THIS Video from Eric "O" of SMA (South Main Auto) performs the actual Diagnosis of a GM Truck suffering from the same "C0327" Code. Just have a look over Eric's Shoulder at this event.

His actions illustrate HOW and WHY the Use of a Tech 2 (or the Later MDI or VXDIAG NANO Scanners) are just amazing devices for Diagnosing GM Module Systems on Class 2 Networks, then Pin-Pointing Problems and Finding Solutions to Electronic and Mechanical Issues:

 

Roamingdoc

Original poster
Member
Dec 23, 2012
34
Prescott, AZ
Wow... that is an amazing scan tool. My mechanic had a 'tech 2' and told me that they had confirmed voltage from the rotary selector to the 'motor'... all normal values. Snap On was the name of the tool...

OF INTEREST... the transfer shift motor comes in two variants apparently (?) one with a five pin plug and the other with a four pin plug (??) I may not have heard the mechanic.
But the "one I need took longer to get" (of course)... anyway... waiting. Thanks!!!!
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
The four pin is likely for the AWD variant, which doesn't have a low range.
 

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