76-43-01A SEP 98 Drivetrain - Slow Or No Engagement of Front

[WorkinStiff]

Can anyone email me the following Technical Service Bulletin:
76-43-01A SEP 98 Drivetrain - Slow Or No Engagement of Front
OR
do you know where I can get a copy?

[shiden_kai]

SLOW OR NO ENGAGEMENT OF FRT. AXLE WHEN 4WD IS SELECTED #76-43-01A -
(09/18/1998)
REVISION: 09/17/98 DIVS INVL 1 5 7

THIS BULLETIN IS BEING REVISED TO ADD INFORMATION TO THE SERVICE PROCEDURE,
ADD A NEW PART NUMBER, AND INCLUDE SCHEMATICS. PLEASE DISCARD CORPORATE
BULLETIN NUMBER 76-43-01 (SECTION 4 - DRIVE AXLE).
______________________________________________________________________

SUBJECT: SLOW OR NO ENGAGEMENT OF FRONT AXLE WHEN 4WD IS SELECTED (REPLACE
FRONT AXLE ACTUATOR)

MODELS: 1988-97 CHEVROLET AND GMC K MODELS EXCLUDING 1988-93 MODELS OVER
8500# GVW

CONDITION:

SOME OWNERS MAY COMMENT THAT THE COLDER THE OUTSIDE TEMPERATURE IS, THE
LONGER IT TAKES FOR THE FRONT AXLE TO ENGAGE WHEN 4 WHEEL DRIVE IS SELECTED,
OR THE FRONT AXLE DOES NOT ENGAGE.

CAUSE:

THE FRONT AXLE ENGAGEMENT ACTUATOR IS A THERMALLY ACTIVATED COMPONENT.
BECAUSE OF THIS CHARACTERISTIC, THE TIME REQUIRED FOR THE ACTUATOR TO
COMPLETE 4 WHEEL DRIVE ENGAGEMENT IS EXTENDED AS THE TEMPERATURE DROPS.

CORRECTION:

REPLACE THE FRONT AXLE ACTUATOR AND INCLUDE THE APPLICABLE WIRING HARNESS
KIT. REFER TO THE PARTS INFORMATION IN ORDER TO DETERMINE WHICH WIRING
HARNESS KIT IS NEEDED.

1996 MODEL TRUCKS WITH A BUILD DATE ON OR AFTER JANUARY 2, 1996 ARE
CONSIDERED AS "96I". IF THE BUILD DATE OF THE TRUCK IS UNKNOWN, VERIFY THE 3
CHARACTER "AXLE CODE" ON THE FRONT AXLE LABEL IN ORDER TO DETERMINE WHICH
WIRE HARNESS TO ORDER.

THIS NEW ACTUATOR USES A MOTOR TO ENGAGE THE FRONT AXLE AND IS NOT AFFECTED
BY TEMPERATURE. ON 1988-93 MODELS WITH A GVW RATING OVER 8500#, THE NEW
ACTUATOR CANNOT BE INSTALLED AND THE THERMAL ACTUATOR WILL REMAIN THE
SERVICE PART.

SERVICE PROCEDURE

1. REMOVE THE FRONT DIFFERENTIAL CARRIER SHIELD, IF EQUIPPED.

2. IF NECESSARY, CLEAN THE AXLE HOUSING IN THE AREA AROUND THE EXISTING
ACTUATOR. DISCONNECT THE ACTUATOR'S ELECTRICAL CONNECTION AT THE FRONT AXLE
HOUSING.

3. REMOVE THE FRONT AXLE ACTUATOR BY UNTHREADING THE ACTUATOR FROM THE AXLE
HOUSING.

4. INSTALL THE SPACER FROM THE WIRING KIT INTO THE AXLE TUBE WITH THE FLAT
SIDE SEATED AGAINST THE SHIFT FORK.

5. INSTALL THE ACTUATOR MOTOR AND TIGHTEN UNTIL THE SHOULDER OF THE ACTUATOR
SEATS AGAINST THE AXLE TUBE.

IMPORTANT: IF BINDING OCCURS BEFORE THE ACTUATOR IS SEATED, REMOVE THE
ACTUATOR AND RESEAT THE SPACER BY PUSHING ON THE SPACER WITH A SCREWDRIVER.
THEN REINSTALL THE ACTUATOR.

ON K3 MODELS WITH THE CAST IRON AXLE TUBE, THERE MAY BE A CASTING BURR WHICH
MAY CONTACT THE EDGE OF THE ACTUATOR. THIS SHOULD NOT CREATE A CONCERN AND
THE ACTUATOR SHOULD SEAT AGAINST THE AXLE TUBE. IF THIS CONTACT REMAINS A
CONCERN, USE A DIE GRINDER IN ORDER TO REMOVE THE BURR.

6. CONNECT THE SERVICE HARNESS CONNECTOR TO THE ACTUATOR AND CONNECT THE
2-PIN CONNECTOR TO THE MATING CONNECTOR AT THE AXLE. FOR 1994 TO CURRENT
MODELS, IN THE CASE OF A COMPLETE AXLE REPLACEMENT, REFER TO FIGURE 1.

7. ROUTE THE WIRING HARNESS ALONG THE EXISTING HARNESS ON THE RIGHT SIDE OF
THE VEHICLE. ROUTE CKT 241 (BRN) OVER THE TOP AND TO THE LEFT OF THE
TRANSMISSION. SECURE THE HARNESS USING PLASTIC TIES.

8. FOR 1995-97 INTERIM VEHICLES, LOCATE THE 4-WIRE CONNECTOR (C120) ON THE
LEFT SIDE OF THE TRANSMISSION. SPLICE THE BRN WIRE OF THE ACTUATOR HARNESS
INTO CAVITY D OF CKT 241 (BRN) ON THE ENGINE SIDE OF CONNECTOR C120. FOLLOW
THE SPLICING PROCEDURE DESCRIBED IN SECTION 8A (ELECTRICAL DIAGNOSIS REPAIR
PROCEDURES) OF THE APPLICABLE SERVICE MANUAL.

IMPORTANT: THE NEW FAST AXLE ACTUATOR REQUIRES ONLY 1 SPLICE. - FOR 1993 AND
PRIOR VEHICLES, SPLICE INTO CKT 50 (BRN) BETWEEN CONNECTOR C152 AND GT101
(FIGURES 2,3,4). - FOR 1994 VEHICLES, SPLICE INTO CKT 50 (BRN) BETWEEN
CONNECTOR C152 AND P101 (FIGURES 5,6). - FOR 1995-97 VEHICLES, SPLICE INTO
CKT 241 (BRN) BETWEEN CONNECTORS C120 AND C100 (FIGURE 7).

NOTICE: CONNECTIONS MUST BE WATER TIGHT IN ORDER TO PREVENT WATER FROM
ENTERING THE CIRCUIT AND CAUSING DAMAGE TO THE COMPONENTS.

9. ON K3 MODELS, INSTALL THE DELAY RELAY, INCLUDED AS PART OF THE WIRING
HARNESS KIT, AT THE ENGINE SIDE OF THE BULKHEAD, ADJACENT TO THE EXISTING
RELAY. MOUNT THE NEW RELAY WITH SELF-DRILLING FASTENER, P/N 22510339. ROUTE
AND SECURE THE RELAY WIRE HARNESS BEHIND THE RIGHT OXYGEN SENSOR HEAT
SHIELD.

10. VERIFY SYSTEM OPERATION. WHEN SHIFTING THE TRANSFER CASE, YOU SHOULD
HEAR THE ACTUATOR MOTOR OPERATE.

IMPORTANT: THIS RELAY INCORPORATES A 5 SECOND DELAY FOR THE FRONT AXLE TO
ENGAGE IN ORDER TO ALLOW THE TRANSFER CASE SYNCHRONIZER TO ENERGIZE.

FOR 88-93 VEHICLES, IF THE AXLE HAS TO BE REPLACED, USE JUMPER HARNESS P/N
15313272. CKT 1695 (BLK/WHT) FITS INTO CAVITY A OF THE FAST ACTUATOR. THE
CIRCUIT INCLUDES THE CABLE SEAL AND THE TERMINAL PIN. THIS CIRCUIT PLUGS
INTO THE 5-PIN AXLE ACTUATOR CONNECTOR.

11. DO THE FOLLOWING STEPS IN ORDER TO INSTALL JUMPER HARNESS P/N 15313272:

1. LOCATE THE AXLE ACTUATOR 5-PIN CONNECTOR ON THE SERVICE ACTUATOR WIRING
HARNESS AND REMOVE THE TPA. 2. REMOVE AND DISCARD THE CAVITY PLUG FROM
CAVITY A. 3. INSTALL CKT 1695 LEAD (BLK/WHT) FROM THE JUMPER HARNESS THAT
HAS THE CABLE SEAL AND TERMINAL INTO AXLE ACTUATOR CONNECTOR CAVITY A. 4.
REINSTALL THE TPA ON THE 5-PIN CONNECTOR. 5. INSTALL THE SERVICE ACTUATOR
HARNESS 5-PIN CONNECTOR INTO THE AXLE ACTUATOR. 6. CONNECT JUMPER HARNESS
2X2 CONNECTOR INTO THE EXISTING VEHICLE 4WD MATING CONNECTOR. 7. STRAP THE
JUMPER HARNESS AND THE SERVICE HARNESS TO THE TAB ON THE AXLE TUBE.

PARTS INFORMATION:

P/N DESCRIPTION QTY --- ----------- ---

26060073 ACTUATOR ASM, FRT DRIVE AXLE 1 22510339 FASTENER 1 15313272
HARNESS, JUMPER (Z SPLICE)(88-93 K1-3) 1

AXLE CODE 12376316 KIT, ACTUATOR WIRING HARNESS (88-96I K1,2) ZLS, ZLT, ZLW
ZLX, ZLY 12376317 KIT, ACTUATOR WIRING HARNESS (96I-97 K1,2) ZWA, ZWB, ZWD
ZWF, ZWG 12376318 KIT, ACTUATOR WIRING HARNESS (94-96I K3) ZLX, ZLY, ZLZ
12376319 KIT, ACTUATOR WIRING HARNESS (96I-97 K3) ZWF, ZWG, ZWH

PARTS, EXCEPT P/N 15313272, ARE CURRENTLY AVAILABLE FROM GMSPO. P/N 15313272
IS EXPECTED TO BE AVAILABLE 9-21-98.

WARRANTY INFORMATION:

SOME OWNERS WITH ACTUATORS THAT ARE OPERATING AS DESIGNED (5-30 SECONDS
ENGAGEMENT TIME) MAY CHOOSE TO UPGRADE TO THE FAST ACTUATOR AT THEIR OWN
EXPENSE. THE FAST ACTUATOR IS A NEW PRODUCT ENHANCEMENT AND SHOULD NOT BE
USED TO REPLACE ACTUATORS THAT ARE OPERATING AS DESIGNED.

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION DESCRIPTION LABOR TIME --------- ----------- ----------

F0025 ACTUATOR, FRONT DIFFERENTIAL USE PUBLISHED LABOR LOCKING, REPLACE
OPERATION TIME

N6112 WIRING AND/OR CONNECTOR-REPAIR USE PUBLISHED LABOR OPERATION TIME

IMPORTANT: LABOR OPERATION IS CODED TO BASE VEHICLE COVERAGE IN THE WARRANTY
SYSTEM.

FIGURES: 00 ATTACHMENTS: 07

ATTACHMENT 1 - FOUR WHEEL DRIVE INDICATOR SCHEMATIC (94 TO CURRENT)
ATTACHMENT 2 - FOUR WHEEL DRIVE INDICATOR SCHEMATIC (88-93 MODELS)
ATTACHMENT 3 - FOUR WHEEL DRIVE INDICATOR SCHEMATIC (93 4L60E MODELS)
ATTACHMENT 4 - FOUR WHEEL DRIVE INDICATOR SCHEMATIC (93 4L80E MODELS)
ATTACHMENT 5 - FOUR WHEEL DRIVE INDICATOR SCHEMATIC (94 W/K3) ATTACHMENT 6 -
FOUR WHEEL DRIVE INDICATOR SCHEMATIC (94 W/O K3) ATTACHMENT 7 - FOUR WHEEL
DRIVE INDICATOR SCHEMATIC (95 TO CURRENT MODELS)

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS,
NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF
CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT
COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED
TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO
DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME
THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE
THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL
MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE
INFORMATION.

[WorkinStiff]

shiden_kai,
Thanks for the post. Just what I needed.

"shiden_kai" <violet-lighte...@hotmail.com> wrote in message news:<eSOI9.55378$fk5.5...@news0.telusplanet.net>...

[Noah98]

Where can I get the wiring diagrams? I've found the text everywhere but no
diagrams. I have a 94 K1500 6.5 TD and just need to know where to splice
the wire. Where is CKT 50 (BRN) between connector C152 and P101???

Thanks.

[Bret Chase]

On Sat, 23 Oct 2004 17:18:36 -0400, "Noah98" <nos...@shreve.net>
wrote:

>:|Where can I get the wiring diagrams? I've found the text everywhere but no

>:|diagrams. I have a 94 K1500 6.5 TD and just need to know where to splice
>:|the wire. Where is CKT 50 (BRN) between connector C152 and P101???
>:|
>:|Thanks.

it's the brown wire that comes out of the connector on the top of the
transfer case.

hth,
Bret
btw.. you'll love the updated actuator... it's awesome

[Noah98]

THANKS! I see it. Do I splice in back at the connector on top of the
transfer case or is there a more accessable location?

Thanks again.

[Bret Chase]

On Sun, 24 Oct 2004 22:40:48 -0400, "Noah98" <nos...@shreve.net>
wrote:

>:|THANKS! I see it. Do I splice in back at the connector on top of the

>:|transfer case or is there a more accessable location?
>:|
>:|Thanks again.

if you're using the retrofit harness, you've only got enough length
to connect to the brown wire at the transfer case. I'm sure you could
break the harness and follow the wire to a drier location if you
wanted to, but I've had mine connected at the xfer case for almost 3
years now w/ no probs.

-Bret

[cqui...@gmail.com]

I know this is like over ten years old this thread, but I had the updated electronic actuator on my truck. I searched for the problem as to why it wouldn't work, and sure enough, the previous owner must have had done the splice weak as it had come off. Fixed my issue, and saved me from re wiring the entire thing. :)

Thanks for all the comments everyone, y'all saves me money.