95 4R 4WD issue.
07-31-2014, 12:13 PM
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95 4R 4WD issue.
Hey guys, and thank you in advance for any help. New to the site and I have not combed through everything yet. So I apologize.
I have a 95 4runner, and the 4wd system is not working. I can hear the transfer case clunk when I change from H2 to H4 or L4. When in L4 I get the low ratio, but only to the rear tires. The front wheels will not spin. I'm lost. As I've never worked on one of these vehicles prior to now. Are there any detailed schematics of the system I can use? And ideas from you guys? All is greatly appreciated!
I have a 95 4runner, and the 4wd system is not working. I can hear the transfer case clunk when I change from H2 to H4 or L4. When in L4 I get the low ratio, but only to the rear tires. The front wheels will not spin. I'm lost. As I've never worked on one of these vehicles prior to now. Are there any detailed schematics of the system I can use? And ideas from you guys? All is greatly appreciated!
07-31-2014, 12:28 PM
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ADD is automatic differential disconnect. Instead of manual hubs this system disconnects your front axle via vacuum from the engine.
Did you just purchase the vehicle? Has the 4wd worked before?
Did you just purchase the vehicle? Has the 4wd worked before?
07-31-2014, 12:31 PM
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Yes I purchased it awhile back and it was working. Really wish it had manual hubs. I live in hell (Arizona) So hoses don't last long. If it is just a vacuum line, is there a printout of where all the lines and components are located?
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07-31-2014, 07:03 PM
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Check out these web articles on the ADD system. They should give you what you need to figure out the problem.
http://www.off-road.com/trucks-4x4/t...tem-19259.html
http://www.toyotasurf.asn.au/techsite/add.htm
http://www.off-road.com/trucks-4x4/t...tem-19259.html
http://www.toyotasurf.asn.au/techsite/add.htm
Last edited by RJR; 07-31-2014 at 07:05 PM.
07-31-2014, 07:05 PM
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Check out this web article on the ADD system. It should give you what you need to figure out the problem.
http://www.off-road.com/trucks-4x4/t...tem-19259.html
http://www.off-road.com/trucks-4x4/t...tem-19259.html
08-01-2014, 08:55 PM
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It doesn't take much. I've been able to move the actuator just sucking on the hose with my mouth, so that's only a few inches. I would imagine 10 inches or so would be a worst case number.
08-01-2014, 11:56 PM
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So far I have discovered no vacuum leaks. The vacuum system holds at 18 inches steadily. I do not know if this is the average number the system should rest at or not though.
I am curious to know how durable/weak the bags in the actuator are. Do they typically fail? Or do they stand up to the test of time?
I am curious to know how durable/weak the bags in the actuator are. Do they typically fail? Or do they stand up to the test of time?
08-02-2014, 06:20 AM
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It's possible the problem is in the ADD actuator itself, but it's far more likely that you have an electrical or vacuum hose issue that is preventing proper vacuum from getting to the actuator.
What have you checked so far? Here's how I would troubleshoot it.
- Make sure all vacuum hoses are good and are connected properly, both at the differential and at the vacuum switches on the passenger-side fender under the hood. Faulty vacuum hoses/connections are probably the #1 cause of ADD problems.
- With the engine OFF and the ignition ON, move the shift lever from 2wd to 4wd. You should hear the ADD relay click under the dash, and if you stick your head out the window with the hood open, you should hear the vacuum switches on the fender click. If neither of those click, you have an electrical problem, probably in the 4wd sense switch in the transfer case, or the associated wiring.
- If both of those click, start the engine and check for vacuum going to the vacuum switches. Just pull the line off and put your finger over it. Then check that the vacuum changes from one output port to the other as you move the shift lever from 2wd to 4wd.
- If the vacuum checks out on the fender, put the hoses back on and do the same tests at the differential by pulling off the hoses there. Try swapping the hoses to see what effect that has.
- If you have good vacuum at the actuator and it switches from one port to the other properly, then and only then start worrying about the actuator itself.
What have you checked so far? Here's how I would troubleshoot it.
- Make sure all vacuum hoses are good and are connected properly, both at the differential and at the vacuum switches on the passenger-side fender under the hood. Faulty vacuum hoses/connections are probably the #1 cause of ADD problems.
- With the engine OFF and the ignition ON, move the shift lever from 2wd to 4wd. You should hear the ADD relay click under the dash, and if you stick your head out the window with the hood open, you should hear the vacuum switches on the fender click. If neither of those click, you have an electrical problem, probably in the 4wd sense switch in the transfer case, or the associated wiring.
- If both of those click, start the engine and check for vacuum going to the vacuum switches. Just pull the line off and put your finger over it. Then check that the vacuum changes from one output port to the other as you move the shift lever from 2wd to 4wd.
- If the vacuum checks out on the fender, put the hoses back on and do the same tests at the differential by pulling off the hoses there. Try swapping the hoses to see what effect that has.
- If you have good vacuum at the actuator and it switches from one port to the other properly, then and only then start worrying about the actuator itself.
08-02-2014, 01:41 PM
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It's possible the problem is in the ADD actuator itself, but it's far more likely that you have an electrical or vacuum hose issue that is preventing proper vacuum from getting to the actuator.
What have you checked so far? Here's how I would troubleshoot it.
- Make sure all vacuum hoses are good and are connected properly, both at the differential and at the vacuum switches on the passenger-side fender under the hood. Faulty vacuum hoses/connections are probably the #1 cause of ADD problems.
- With the engine OFF and the ignition ON, move the shift lever from 2wd to 4wd. You should hear the ADD relay click under the dash, and if you stick your head out the window with the hood open, you should hear the vacuum switches on the fender click. If neither of those click, you have an electrical problem, probably in the 4wd sense switch in the transfer case, or the associated wiring.
- If both of those click, start the engine and check for vacuum going to the vacuum switches. Just pull the line off and put your finger over it. Then check that the vacuum changes from one output port to the other as you move the shift lever from 2wd to 4wd.
- If the vacuum checks out on the fender, put the hoses back on and do the same tests at the differential by pulling off the hoses there. Try swapping the hoses to see what effect that has.
- If you have good vacuum at the actuator and it switches from one port to the other properly, then and only then start worrying about the actuator itself.
What have you checked so far? Here's how I would troubleshoot it.
- Make sure all vacuum hoses are good and are connected properly, both at the differential and at the vacuum switches on the passenger-side fender under the hood. Faulty vacuum hoses/connections are probably the #1 cause of ADD problems.
- With the engine OFF and the ignition ON, move the shift lever from 2wd to 4wd. You should hear the ADD relay click under the dash, and if you stick your head out the window with the hood open, you should hear the vacuum switches on the fender click. If neither of those click, you have an electrical problem, probably in the 4wd sense switch in the transfer case, or the associated wiring.
- If both of those click, start the engine and check for vacuum going to the vacuum switches. Just pull the line off and put your finger over it. Then check that the vacuum changes from one output port to the other as you move the shift lever from 2wd to 4wd.
- If the vacuum checks out on the fender, put the hoses back on and do the same tests at the differential by pulling off the hoses there. Try swapping the hoses to see what effect that has.
- If you have good vacuum at the actuator and it switches from one port to the other properly, then and only then start worrying about the actuator itself.
I will look into all of this between today and tomorrow. I'll give an update on what I find and where. I can't thank you enough for providing me with all of this info. I've been a Toyota owner since I could drive, this just happens to be my first 4Runner.
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