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Old 02-15-2012, 08:34 PM   #1
TennesseeZ
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Front axle actuator questions (pics)

1992 Chevrolet K2500, 5.7, 700r4. The 4X4 quit working, it's blowing the fuse. I think I've isolated it to frayed wires where they go into the front axle actuator, but haven't repaired it yet. A while back, I picked up a later model actuator at the J/Y. Here's my questions: the newer actuator is noticeably shorter from the seat (base of threads) out. It's right at 3/4" shorter. Will it work in my axle, to replace the one on the left?

Also the newer one is 3 wire, the original is 2 wire. If I was to use the newer one (if it will interchange), how do I wire it? There is a black, brown, and looks to be green wire.

Here's the pics:
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Last edited by TennesseeZ; 02-15-2012 at 08:40 PM.
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Old 02-16-2012, 01:53 AM   #2
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Re: Front axle actuator questions (pics)

Yes the newer one should work. Can't remember the wiring for it off the top of my head. Might try a google search think that's where I found the info when I did mine or I am sure someone else will chip in on here.
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Old 02-16-2012, 08:40 AM   #3
TennesseeZ
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Re: Front axle actuator questions (pics)

Thanks!
I've been researching this for the last couple hours, and here's what I think I've learned;

GM has issued a service bulletin addressing installing the newer model actuator (electric motor driven) to replace the older (thermal actuated) one. They have also made available a wiring harness for the installation. The wiring harness kit seems to include a spacer for the actuator.

Here's a couple links to the info: http://www.fullsizechevy.com/forum/g...tor-years.html

http://www.justanswer.com/chevy/2vrb...tuator-88.html

The second one seems to have a copy of the TSB, but it's not real clear to me. The first lists the part numbers more clearly.

There are different part numbers depending on what year and model truck is being upgraded.

The harness for my truck (1992 K 2500, 6 lug) is available from Dorman through local parts stores. The number is Dorman 600-600, it varies in price from just under $50 to around $55, (plus 9.75% tax here), which puts it around $55-$60, and seems it must be ordered. Rock has it for just under $40 including shipping.

The harness seems to have several feet of wiring, some of which is insulated from heat.
This leads me to beleive the splice will probably be somewhere near the transfer case/floor mounted actuator lever area, and will be routed near the exhaust system. The spacer does not seem to be included, unless it's the small circular black thing that looks like a plug.

The TSB gives different locations to splice the new harness into the existing one, depending on application.

I have not yet located the connectors mentioned for my installation, (For 1993 and prior vehicles, splice into CKT 50 (BRN) between connector C152 and GT101). I'm not sure if I have a schematic that would show these connectors, as I have misplaced the wiring supplement supplied with my Helms manual, and have not yet found it in the Chiltons. But I'm pretty sure I can find a brown wire in the transfer case area. Just don't know whether to splice before or after the transfer case switch.

I think I'm going to order the harness from Rock, as I have something else to drive, and can also drive the K2500 without 4X4 if necessary.

It is also possible to install the newer actuator using a dash mounted toggle switch, there is an aftermarket cable operated kit available, and a kit to permantly lock the axle (all available from Rock), but I plan to use the later model actuator and Dorman harness.

If I've missed anything, or you can identify the connectors, please help me out.
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Last edited by TennesseeZ; 02-16-2012 at 09:25 AM.
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Old 02-16-2012, 10:35 AM   #4
stevejohnson48
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Re: Front axle actuator questions (pics)

Quote:
Originally Posted by TennesseeZ View Post
1992 Chevrolet K2500, 5.7, 700r4. The 4X4 quit working, it's blowing the fuse. I think I've isolated it to frayed wires where they go into the front axle actuator, but haven't repaired it yet. A while back, I picked up a later model actuator at the J/Y. Here's my questions: the newer actuator is noticeably shorter from the seat (base of threads) out. It's right at 3/4" shorter. Will it work in my axle, to replace the one on the left?

Also the newer one is 3 wire, the original is 2 wire. If I was to use the newer one (if it will interchange), how do I wire it? There is a black, brown, and looks to be green wire.

Here's the pics:
Change it over to a 4x4 posi lock (cable operation)the thermo units are junk
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Old 02-16-2012, 10:52 AM   #5
TennesseeZ
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Re: Front axle actuator questions (pics)

Quote:
Originally Posted by stevejohnson48 View Post
Change it over to a 4x4 posi lock (cable operation)the thermo units are junk
Quote:
Originally Posted by TennesseeZ View Post
It is also possible to install the newer actuator using a dash mounted toggle switch, there is an aftermarket cable operated kit available, and a kit to permantly lock the axle (all available from Rock), but I plan to use the later model actuator and Dorman harness.
I'm going with the electric actuator, thanks for your input.
I've ordered the harness from Rock, If it tells me exactly where to make the splice I should be in business............
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93 Yukon
89 Silverado Z71 SWB Sport
91 K 2500 Silverado "Lobuk-Worktruk"

A MAN OF HONOR DOES NOT LIE, CHEAT, OR STEAL, NOR TOLERATE THOSE WHO DO.

Gettin' old ain't for sissies.

Last edited by TennesseeZ; 02-16-2012 at 11:31 AM.
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Old 02-17-2012, 09:57 PM   #6
TennesseeZ
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Re: Front axle actuator questions (pics)

I ordered the harness yesterday, looking for it Monday probably. Last night I spread out the bare wires and put silicone on it, just temporary. Put it back in today and put in a new fuse, thinking it would work till I got the harness. It blew the fuse as soon as I tried it in 4HI, so I guess the actuator wasn't the problem. I don't have a schematic to figure out where the wires go, so I guess I'll replace the TC switch tomorrow. I really like to test as opposed to replacing, but I don't have a diagnostic flow chart on it or a schematic. Can anybody tell me what I should test? Does the fuse supply power to the switch on top of the TC, and when closed (TC in 4HI, for instance) it sends power to the front axle actuator? Thanks for any help.
__________________
93 Yukon
89 Silverado Z71 SWB Sport
91 K 2500 Silverado "Lobuk-Worktruk"

A MAN OF HONOR DOES NOT LIE, CHEAT, OR STEAL, NOR TOLERATE THOSE WHO DO.

Gettin' old ain't for sissies.
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Old 02-19-2012, 02:41 AM   #7
stevejohnson48
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Re: Front axle actuator questions (pics)

you might be better off leaving the unit off and hook a multimeter testing the out put at the connection before plugging it in!!!!switch back and fourth to find find out the reading??? if 12 volts,as I think mine was at the plug ??? you could run a jump wire from the battery to test the unit off the diff to see if its working, you might even go as far to put an inline fuse in your jump wire lead if you have any doubts about the performance of the unit it self???/if the weather or unit is cold it takes some time for the oil to expand so that the piston moves,that why I replaced mine on my 90 k1500,with a cable posi,when I was pulling my boat out on the boat ramp (2 wheel drive) the back tires broke lose,so I put it in four HI ,light came on and I thought I was good to go,no way,The tires broke lose again and after about 3 sec. the thing engaged with a load bang, I mean a BANG !!!
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Old 02-19-2012, 02:46 AM   #8
stevejohnson48
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Re: Front axle actuator questions (pics)

Quote:
Originally Posted by stevejohnson48 View Post
you might be better off leaving the unit off and hook a multimeter testing the out put at the connection before plugging it in!!!!switch back and fourth to find find out the reading??? if 12 volts,as I think mine was at the plug ??? you could run a jump wire from the battery to test the unit off the diff to see if its working, you might even go as far to put an inline fuse in your jump wire lead if you have any doubts about the performance of the unit it self???/if the weather or unit is cold it takes some time for the oil to expand so that the piston moves,that why I replaced mine on my 90 k1500,with a cable posi,when I was pulling my boat out on the boat ramp (2 wheel drive) the back tires broke lose,so I put it in four HI ,light came on and I thought I was good to go,no way,The tires broke lose again and after about 3 sec. the thing engaged with a load bang, I mean a BANG !!!
you can also with the add of a multimeter check the out put on both sides of the switch !!Steve
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