4 Wheel Drive Help

[msc5195]

I just bought a new 4 wheel drive actuater for my 96 Silverado and it came with a new wiring harness. Does anyone know how to wire the new harness?

[Gooseneck]

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)

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.

COPYRIGHT 1998 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.



GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these 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 your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


© Copyright General Motors Corporation. All Rights Reserved.


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Document ID# 533269
1993 Chevrolet/Geo Chevy Suburban - 4WD

[anianno]

Hello does anybody have the attachments to view the schematics for the 4wd actuator modification??? I need the schematics to troubleshoot a truck that was modified Thanks for any help!!

[Jeremy-WI]

On a vehicle updated with the new actuator, check the TCASE and 4x4 fuses to make sure they are good. With the ignition on and a 4 wheel drive mode selected, at the front actuator harness you should have 12v at the brown and light blue wire. With igntion on and 2WD selected you should have power only at the brown wire

[anianno]

Originally Posted by Jeremy-WI

On a vehicle updated with the new actuator, check the TCASE and 4x4 fuses to make sure they are good. With the ignition on and a 4 wheel drive mode selected, at the front actuator harness you should have 12v at the brown and light blue wire. With igntion on and 2WD selected you should have power only at the brown wire

I presume the 3rd wire (i dont know the color) is ground all the time?? I will check it asap and let you know. I know currently there is no power at the connector at all in 2wd that is why the actuator wont run back in. Thanks again!!!

[Jeremy-WI]

well that would indicate a problem with the brown wire that is usually connected to another brown wire at the TCase switch, it may be that the splice is bad

[anianno]

Yea I think your right. I'll check it out as soon as my buddy can bring the truck over to me. I replaced the transfer case (he ran it dry) and I noticed a scotch lock connector ,taped into the t case switch ,that was all siliconed up but at the time I didnt know about the modification. I bet that is the problem.Thanks again talk to ya soon

[anianno]

I checked the truck out today and found something very interesting. The brown wire at the front axel actuator is spliced into the light blue wire at the t case switch. I believe this is incorrect. I think it should be spliced into the brown wire at the t case switch which would provide 12v to the brown wire all the time. I will switch the wires tomorrow . I didnt switch the wires because I couldnt figure out for sure what the 3rd wire was for at the t case sw?? any ideas?? maybe a light control?? I checked the t case switch in 2 and 4 wheel drive and there is no continuity between that terminal and either of the others. (the switch could be bad though i'm not sure) Also this mod was done by the dealer about 5 years ago so I figured it couldnt be wired wrong that long without the owner knowing. he origonally brought it back for a no engagement complaint. aftering thinking about it for a few minutes I realised that the mod was never done right and with the actuator engageing the front axel but the t case disconnecting the drive shaft he would never have known. Also it would go into 2wd normally but spin the drive shaftall the time. That would also explain why the front u joints were worn out.This all came about when I changed his t case (he ran it dry) and noticed the front drive shaft wouldnt spin by hand in 2wd. I hope you can follow all this!!!I'll keep you updated on my progress!!!

[rickeys]

Interesting, I have nearly the same problem. My actuator is stuck in the 4wd position. I checked the voltages at the connector and found no voltage. At the transfer case I could only get 12V at one wire in any position. Does anyone have a schematic of the 4wd system?

thanks
rickey

[Jeremy-WI]

anianno, the brown from the adapter harness should be hooked to brown at transfer case switch.

rickeys, what year vehicle? Do you have a metal front axle actuator or plastic?

[rickeys]

My PU is a 95. It does have the replacement actuator, but I do believe that it's miswired. Somewhat hard to get a reference as most of the connections have been cut off with wires directly spliced. At present, the terminal off the tcase switch that has 12V when in 4wd is connected to the blue wire on the actuator terminal. According to two GM service folks, the actuator wiring harness - the brown wire should splice into the tcase switch that has 12V when in 4wd. I can connect the brown to the proper terminal off the tcase switch, but I don't know what originally connected to this terminal. That is, I should be splicing and not replacing. How was the orginal themal actuator, tcase switch, and indicator switch on differential wired. Or, how does the new acutator operate, 12V on brown and 12V on blue as described above?Boy, a schematic would really help. The GM service departments refused to print off a copy off their computers.

I've been to our local public library trying to find an electrical schematic. None of the manuals with schematics show the 4wd schematic. One would that think that one would be available.

thanks
rickey

[J-Ri]

Are there any technical schools in your area that have an Automotive Technology course? I'm a student at one (in Iowa), and we have access to 95%+ of the manufacturer information. You may want to try getting it from there. I'm out for Christmas break already, but when I go back (Jan 11) I'll see if I can get it for you.

[Jeremy-WI]

the brown wire in the actuator harness should have power any time the ignition is on. The blue wire should only have power in a 4 wheel drive mode. The blue wire also puts power at the front axle switch which basically just causes the 4x4 light to quit blinking and go solid, or light up the front axle in the display(manual transfer case). The only real difference between the wiring of the thermal and electric front axle actuators is that the brown wire is not found at the front axle actuator connector with thermal because the thermal cools and disengagess without power to the blue and the electric uses the blue just to know when to engage and needs the brown to engage and disengage

[rickeys]

Much thanks!!! I think I'm close. The brown gets power with the key on, I assume that this power comes from the tcase switch terminal that has power with the key on while the brown must get power from the tcase switch terminal that has power with the 4wd engaged?? Is this correct?

How does the indicator switch wire? It appears to have 3 wires, one brown and two black. You stated that the blue wire also puts power to the indicator switch, which wire?

thanks
rickey

[rickeys]

I rewired the actuator and it works as it should. My next step is to get the indicators to work. The indicator switch on the differential appears to be bad. This will have to be a item that is ordered. Because of the bad wiring, I will be "running" new wiring for the indication. The PU has manual transfer case shifter. The indication is two lights. I assume that the light under the 2wd spot lights while in 2WD while the light under the 4WD spot lights when in 4WD. Is this assumption correct? Thanks all for the help. The interesting thing is that the service managers at two of the local dealerships were wrong in the wiring of the actuator........

thanks
rickey