4wd Issue
November 3rd, 2019, 7:09 AM
#1
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4wd Issue
So, I've scoured the web and could not find anything on this particular issue although there were similar ones that stopped short of being helpful. I have an '02 Suburban 1500 LT that I listed for sale and when a potential buyer declined, I knew I had to fix the many warning lights before trying to sell it again. So I de-listed it and fixed them all except for the "Service 4wd" light that actually only comes on when you use the 4wd but still need to fix the issue. (The "Service Engine Soon" light was fixed by giving it an oil change and replacing the oxygen sensors. The "ABS" and "Brake" lights I fixed by reflowing the solder joints on the EBCM).
The 4wd works but.....when I switch to 4Lo or 4hi it does so without issue. The problem is when I stop and put in neutral then press the 2hi button, I can hear the transfer case make a noise as if it worked except when I put it back into Drive it just revs with no movement. It isn't until I turn off the car, put it in Park, restart it, and then put it in Drive that it goes back into 2hi.. So I can shift into 4Lo or 4hi normally, but to get back into 2hi I have to turn off the engine. Is anybody familiar with this or what the cause may be?
The 4wd works but.....when I switch to 4Lo or 4hi it does so without issue. The problem is when I stop and put in neutral then press the 2hi button, I can hear the transfer case make a noise as if it worked except when I put it back into Drive it just revs with no movement. It isn't until I turn off the car, put it in Park, restart it, and then put it in Drive that it goes back into 2hi.. So I can shift into 4Lo or 4hi normally, but to get back into 2hi I have to turn off the engine. Is anybody familiar with this or what the cause may be?
November 3rd, 2019, 8:48 AM
#2
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So, I've scoured the web and could not find anything on this particular issue although there were similar ones that stopped short of being helpful. I have an '02 Suburban 1500 LT that I listed for sale and when a potential buyer declined, I knew I had to fix the many warning lights before trying to sell it again. So I de-listed it and fixed them all except for the "Service 4wd" light that actually only comes on when you use the 4wd but still need to fix the issue. (The "Service Engine Soon" light was fixed by giving it an oil change and replacing the oxygen sensors. The "ABS" and "Brake" lights I fixed by reflowing the solder joints on the EBCM).
The 4wd works but.....when I switch to 4Lo or 4hi it does so without issue. The problem is when I stop and put in neutral then press the 2hi button, I can hear the transfer case make a noise as if it worked except when I put it back into Drive it just revs with no movement. It isn't until I turn off the car, put it in Park, restart it, and then put it in Drive that it goes back into 2hi.. So I can shift into 4Lo or 4hi normally, but to get back into 2hi I have to turn off the engine. Is anybody familiar with this or what the cause may be?
The 4wd works but.....when I switch to 4Lo or 4hi it does so without issue. The problem is when I stop and put in neutral then press the 2hi button, I can hear the transfer case make a noise as if it worked except when I put it back into Drive it just revs with no movement. It isn't until I turn off the car, put it in Park, restart it, and then put it in Drive that it goes back into 2hi.. So I can shift into 4Lo or 4hi normally, but to get back into 2hi I have to turn off the engine. Is anybody familiar with this or what the cause may be?
November 3rd, 2019, 2:11 PM
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I don't think it's the selector switch because the light is always present and indicating correctly. From what I gathered, the ones that were bad usually didn't have any indicator light working at all, or were erratic with a mind of its own. The ground underneath the drivers side that is bolted to the frame is also mentioned as a common problem but I took it off, sanded it clean and put it back on so it's not that. Then I saw a couple of videos on Youtube where they replace the encoder ring and the issue is fixed, so I ordered one and when I removed the encoder motor it turned out (much to my dismay) that it only works on the 2003 and later. The '02 transfer case motor was completely different. The gear wasn't round in shape it was more like a pie wedge and I wasn't able to find the counterpart that would have been the encoder ring for that one.
November 3rd, 2019, 3:30 PM
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I don't think it's the selector switch because the light is always present and indicating correctly. From what I gathered, the ones that were bad usually didn't have any indicator light working at all, or were erratic with a mind of its own. The ground underneath the drivers side that is bolted to the frame is also mentioned as a common problem but I took it off, sanded it clean and put it back on so it's not that. Then I saw a couple of videos on Youtube where they replace the encoder ring and the issue is fixed, so I ordered one and when I removed the encoder motor it turned out (much to my dismay) that it only works on the 2003 and later. The '02 transfer case motor was completely different. The gear wasn't round in shape it was more like a pie wedge and I wasn't able to find the counterpart that would have been the encoder ring for that one.
November 3rd, 2019, 11:24 PM
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This encoder/actuator unit should fit your 2002 Chevy Suburban 1500. It does come with either 4 or 8 pin connector, so you will have to see what your vehicle has:
https://www.amazon.com/Transfer-Actu...+Suburban+1500
https://www.amazon.com/Transfer-Actu...+Suburban+1500
November 4th, 2019, 1:40 AM
#6
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https://www.rockauto.com/en/moreinfo...1380327&jsn=10
You can purchase the Cardone unit for almost half that price. Your gasket is reusable but new ones are available. You will have to synchronize the actuator to the same gear it was in when you last used it, but if you can get it into neutral that would be better. You can do this once the actuator is removed, IF the motor still works at all off your vehicle with the wires connected to the unit, with the ignition key turned to the "ON" position.
You'll have to remove your driveshaft, so make sure that you don't lose the bearing end caps on the U-joint,(Electrical tape works good) and will have to replace the driveshaft boot clamp (make sure the boot looks good to go). I would highly suggest using dialectical grease on the electrical connectors to keep dust, salt and water out.The three bolts holding the unit to your transfer case will be tightened down to 15 foot pounds (I'd use Permatex Blue on the threads) once the new unit is in place and the driveshaft installed back, I would use the synchomesh transfer case fluid that GM recommends, but Royal Purple also make a great synchomesh fluid, as do others.
You can select almost any of these synchomesh fluids on this Amazon page (no gear oils) as your lubricant and you will do well.The transfer case will hold around 2 US quarts of fluid. I would not recommend using automatic transmission fluid to fill your transfer case. Once it starts coming out the fill hole, it's full and you can tighten down the plug and replace the skid pan..
Last edited by oilcanhenry; November 4th, 2019 at 4:45 AM.
November 4th, 2019, 8:18 AM
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Yes, Here is a genuine ACDelco uniit listed for your 2002 Chevy Suburban 1500 at Rock Auto:
https://www.rockauto.com/en/moreinfo...1380327&jsn=10
You can purchase the Cardone unit for almost half that price. Your gasket is reusable but new ones are available. You will have to synchronize the actuator to the same gear it was in when you last used it, but if you can get it into neutral that would be better. You can do this once the actuator is removed, IF the motor still works at all off your vehicle with the wires connected to the unit, with the ignition key turned to the "ON" position.
You'll have to remove your driveshaft, so make sure that you don't lose the bearing end caps on the U-joint,(Electrical tape works good) and will have to replace the driveshaft boot clamp (make sure the boot looks good to go). I would highly suggest using dialectical grease on the electrical connectors to keep dust, salt and water out.The three bolts holding the unit to your transfer case will be tightened down to 15 foot pounds (I'd use Permatex Blue on the threads) once the new unit is in place and the driveshaft installed back, I would use the synchomesh transfer case fluid that GM recommends, but Royal Purple also make a great synchomesh fluid, as do others.
https://www.amazon.com/s?k=GM+sysnch...ref=nb_sb_noss
You can select almost any of these synchomesh fluids on this Amazon page (no gear oils) as your lubricant and you will do well.The transfer case will hold around 2 US quarts of fluid. I would not recommend using automatic transmission fluid to fill your transfer case. Once it starts coming out the fill hole, it's full and you can tighten down the plug and replace the skid pan..
https://www.rockauto.com/en/moreinfo...1380327&jsn=10
You can purchase the Cardone unit for almost half that price. Your gasket is reusable but new ones are available. You will have to synchronize the actuator to the same gear it was in when you last used it, but if you can get it into neutral that would be better. You can do this once the actuator is removed, IF the motor still works at all off your vehicle with the wires connected to the unit, with the ignition key turned to the "ON" position.
You'll have to remove your driveshaft, so make sure that you don't lose the bearing end caps on the U-joint,(Electrical tape works good) and will have to replace the driveshaft boot clamp (make sure the boot looks good to go). I would highly suggest using dialectical grease on the electrical connectors to keep dust, salt and water out.The three bolts holding the unit to your transfer case will be tightened down to 15 foot pounds (I'd use Permatex Blue on the threads) once the new unit is in place and the driveshaft installed back, I would use the synchomesh transfer case fluid that GM recommends, but Royal Purple also make a great synchomesh fluid, as do others.
https://www.amazon.com/s?k=GM+sysnch...ref=nb_sb_noss
You can select almost any of these synchomesh fluids on this Amazon page (no gear oils) as your lubricant and you will do well.The transfer case will hold around 2 US quarts of fluid. I would not recommend using automatic transmission fluid to fill your transfer case. Once it starts coming out the fill hole, it's full and you can tighten down the plug and replace the skid pan..
The AC Delco is definitely the one to go with. Very costly though but I'm sure it's well wort it in the long run. I think I may just sell it as is and let the new owner deal with it however they see fit. I don't have the 2-300 dollars to put in. Hopefully whoever buys it knows how to do minimal mechanic work. It really is an extremely simple part swap that would save hundreds not paying a shop to do it. Everything else about the vehicle is impeccable and it's just had an oil change.
One more thought....I was amazed at how the EBCM was fixed just by reflowing a few solder joints on the PC board. I couldn't believe it worked! What are the chances that doing the same thing to the TCCM would do the trick?
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November 4th, 2019, 8:55 AM
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I read a little more about what the TCCM does and now I don't think so. My unqualified guess is that it's the transfer case position sensor. On the 2003 and later the transfer case position sensor is that encoder ring located underneath the round gear inside the TC motor, isn't it? I could be totally wrong. If it is, however, then why doesn't the pie wedge gear in the 2002 version of the TC motor have one under it? Where would the TC position sensor be on the "02 Suburban? Why doesn't anything come up on autozone.com when I search for "transfer case position sensor" for an '02 Suburban?
Last edited by Special Guest; November 4th, 2019 at 9:00 AM.
November 4th, 2019, 4:52 PM
#9
CF Monarch
I read a little more about what the TCCM does and now I don't think so. My unqualified guess is that it's the transfer case position sensor. On the 2003 and later the transfer case position sensor is that encoder ring located underneath the round gear inside the TC motor, isn't it? I could be totally wrong. If it is, however, then why doesn't the pie wedge gear in the 2002 version of the TC motor have one under it? Where would the TC position sensor be on the "02 Suburban? Why doesn't anything come up on autozone.com when I search for "transfer case position sensor" for an '02 Suburban?
Cost if done in shop to swap out the TC encoder at a private repair shop: $500 to $750 USD. Even more, if it was a dealership. You should see the extreme markup they have on automotive air conditioning systems, my speciality. I've seen people who paid over $700 dollars, just to install a new A/C compressor clutch, not the compressor itself! Unbelievable!
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