On the dyno....but no AWD!!

[Mr. Pockets]

Originally posted by UberRoo
The second point is that if you noticed a loss of AWD, i.e., the front wheels spin while the rear wheels do not, you should get a code for speed sensor two because it detects an extreme speed differential which should not exist under any [normal] condition. The exception to this is that you will not get the code if you never do anything that would cause the front wheels to spin significantly faster than the rear wheels.

Your first point was addressed already, so I'll brutally and comprehensively destroy this one...with a question.



As you pointed out, if you never did anything that caused a major speed differential, you'd never see an error code. So let's assume that's the case with Bill's car. If he just ran the car on the dyno a couple times and them went back to driving it on the road like he normally does, would the computer detect a fault enough times to record it? As I understand it, a fault has to be detected a few times before the TCU will say, 'okay, I have something to tell you.' I've seen this myself when I tried disconnecting the infamous resistor. The power light didn't blink on startup for the first two or three starts after I disconnected it.

[UberRoo]

Originally posted by Chiketkd
First, check out UberRoo's locker which shows a clutch basket repair he undertook. When I PM'd UberRoo about it, he mentioned that when the clutch basket goes out, there's some serious metallic grinding noises you'll hear along with trans fluid leaking from the rear of the trans (where the driveshaft comes out from the transfer clutch).

Whoa! Hold your horses! We must have been discussing something else, because in my case there was no pronounced noises (from a broken clutch basket) or leaking fluid. The sound of duty solenoid C clicking is actually pretty audible when the engine is off, at least it's louder than I thought it would be.


As for installing the FWD fuse to help protect things, I'm not sure this is of any consequence, but it couldn't hurt anything either.


Regarding how many times a fault must be detected to register a code, I don't know how the TCU figures this one out. I do however know that it's very sensitive to any differential in speed in speed sensor two, at it detected a problem in my transmission even when drove it like a little old lady. Also, are you referring to current codes or latent codes? Again, I'm not sure how the TCU decides these things, but you might just go find a parking lot and light up the front wheels a few times and immediately check for a current code. ...?...


The mismatched tire problem would certainly do it, which qualifies as abuse, but your point is taken. This would most definitely register a code for wheel speed sensor two. In SVXRide's case, did the AWD work before, or are you uncertain about it's previous condition?

[SVXRide]

Originally posted by Chiketkd
$60 for the solenoid is just the part alone when ordered from red95svx with his great discount!

If your clutch basket is messed up, the entire assembly could run in the $700-800 range for parts alone. However, from your description, I seriously doubt that's the problem - and here's why...

First, check out UberRoo's locker which shows a clutch basket repair he undertook. When I PM'd UberRoo about it, he mentioned that when the clutch basket goes out, there's some serious metallic grinding noises you'll hear along with trans fluid leaking from the rear of the trans (where the driveshaft comes out from the transfer clutch).

If your ATF level is fine and if you've heard no metallic grinding noises, then I'm sure it's just the electrical solenoid that's messed up.

-Chike

Chike,
I haven't noticed any fluid leaking from the rear of the trans (now the front seal...that's another question) or any metallic grinding noises. Definitely looks like I'm going to play Detective this weekend!
-Bill

[Chiketkd]

Hope I didn't misinterpret what you said...

-Chike

Originally posted by UberRoo
Whoa! Hold your horses! We must have been discussing something else, because in my case there was no pronounced noises (from a broken clutch basket) or leaking fluid. The sound of duty solenoid C clicking is actually pretty audible when the engine is off, at least it's louder than I thought it would be.

[Chiketkd]

Good luck being Inspector Gadget this weekend Bill!

-Chike

Originally posted by SVXRide
Definitely looks like I'm going to play Detective this weekend!
-Bill

[SVXRide]

I'm fairly certain the AWD worked before, as I had my Maryland emissions inspection a little over a month ago and they ran it on a 4 wheel dyno and all four wheels turned.
Curiousier and curiousier (where is that Cheshire cat....)
-Bill

[UberRoo]

Originally posted by Chiketkd
Hope I didn't misinterpret what you said...
-Chike

I looked at the message. We were contemplating a 'jerking' from your transmission and the possibly that maybe the output shaft or bearing was damaged. ...and a damaged output shaft or bearing that would cause any jerking from your transmission would probably leak like milk from my nose if I heard a funny joke. (Might sound the same too.) In any case, we discussed the output shaft and clutch basket in nearly the same breath. So again, the clutch basket does not seem to make any noise. (An automotive stethoscope would probably be able to detect that, but pulling the speed sensor is easier and probably more reliable.)

[Chiketkd]

Interesting.

I had my dealer hook it up to their scanner and it's my Solenoid C taht's the issue. Thing is, it isn't completely malfunctioning so sometimes my awd is engaged and at other times it isn't. As a result, it can cause a 'clunking' when I'm driving along a perfectly straight road at a steady speed, when the Solenoid decides to work again!

-Chike

Originally posted by UberRoo
I looked at the message. We were contemplating a 'jerking' from your transmission and the possibly that maybe the output shaft or bearing was damaged. ...and a damaged output shaft or bearing that would cause any jerking from your transmission would probably leak like milk from my nose if I heard a funny joke. (Might sound the same too.) In any case, we discussed the output shaft and clutch basket in nearly the same breath. So again, the clutch basket does not seem to make any noise. (An automotive stethoscope would probably be able to detect that, but pulling the speed sensor is easier and probably more reliable.)

[SVXRide]

Well,
I did the "turn the ignition switch on and listen for buzzing sounds" and the TCU diagonostics that Lee put in his 4HEAT documents and came up empty...
I didn't hear any buzzing except when I first turned the key to "on" -- got under the car and didn't hear any continuous buzzing noise from the transmission area -- is solenoid C supposed to continue to cycle as long as the key in "on"??
I ran through the TCU procedure and the Power light didn't blink one bit. Question - the car isn't supposed to be running while you do the "manual button on, shift gears, manual button off, shift gears...." process. I'm a little confused, as Lee's document refers to pushing the gas pedal down at the end to disengage the fast idle... I haven't gotten to the diagnostics section of my SVX shop manual yet (volume 2 - which covers the trans), thus the question.
Does anyone know what the size of the pressure port in the transfer case is? I'd like to have a set up ready before I get under the car and remove the plug from the access port.
-Bill

EDIT -- just went back and checked UberROO's comments in an earlier thread -- does the trans have to be in Drive with the key on to get the buzzing noise? I know I had the trans in Park when I did this check.

[SVXRide]

FYI,
This is the procedure I followed - note that it appers to indicate that you do all of it without the engine running.

To perform the TCU self diag test for EXISTING problems
1) Warm up engine by driving at speeds greater than 12mph.
2) Stop vehicle and turn ignition switch OFF.
3) Turn ignition switch ON and make sure POWER indicator lamp comes on.
4) Turn ignition switch OFF.
5) Move selector lever to D and turn manual switch ON.
6) Turn ignition switch ON.
7) Move selector lever to "3" and turn manual switch OFF.
8) Move selector level to "2" and turn manual switch ON.
9) Move selector lever to "1" and turn manual switch OFF.
10) Partially depress accelerator pedal (to turn idle switch off).
11) Check code as displayed on POWER light. Blinking once every 1/4sec is normal.

To perform the TCU self diag test for PREVIOUS problems
1) Warm up engine by driving at speeds greater than 12mph.
2) Stop vehicle and turn ignition switch OFF.
3) Turn ignition switch ON and make sure POWER indicator lamp comes on.
4) Turn ignition switch OFF.
5) Move selector lever to "1" and turn manual switch ON.
6) Turn ignition switch ON.
7) Move selector lever to "2" and turn manual switch OFF.
8) Move selector lever to "3" and turn manual switch ON.
9) Move selector lever to "D" and trun manual switch OFF.
10) Partially depress accelerator pedal (to turn idle switch off).
11) Check code as displayed on POWER light. Blinking once every 1/4sec is normal.

Trouble codes:
11 Duty solenoid A
12 Duty solenoid B
13 Shift solenoid 3
14 Shift solenoid 2
15 Shift solenoid 1
21 ATF temp sensor
22 Atmospheric sensor
23 Engine revolution signal
24 Duty solenoid C
25 Engine torque control signal
31 Throttle sensor
32 Vehicle speed sensor 1
33 Vehicle speed sensor 2

My POWER light didn't blink at all....
-Bill

[UberRoo]

The engine should be OFF when pulling the codes.

For the solenoid noise check, it doesn't matter what gear you're in, as long as you're in a gear [1,2,3,D,R]. Park, or neutral will not work. Make sure the ignition is ON so that the dash warning lights are illuminated.

Remember, the FWD fuse must not be installed to hear the noise. A great way to do this test is to insert and remove the fuse a few times while listening for the noise. You should be able to hear it emanate up through the engine compartment. When you insert the fuse, the noise should fade away, but when you remove it, the noise will immediately return.

Sounds to me that if you don't hear anything, your solenoid isn't working. It's probably jammed. Unless you're not pulling the codes correctly, it seems probable that you have a mechanical problem with the valve body. Somebody mentioned that they had a problem that seemed to be a valve getting jammed shut by hydraulic pressure. When the engines starts, the solenoid is activated and the valve it controls is exposed to hydraulic pressure. If it's not activated when the hydraulic pressure is generated for the first time, it may not jam. (I realize this is not consistent with the noise test.) Perhaps if you cut the wire that controls the solenoid, it may suddenly begin functioning if it un-jams itself. This is kind of a long shot, but it's a place to begin.

You can also tap into the wiring harness and check for continuity of the solenoid, but if you have no codes, it's probably good. Doesn't hurt to check though.

The noise test works very well on my car. Can anyone else confirm that it works for them as well? It takes all of ten seconds to do.

1) Put car in neutral, and turn the key on. No noise.
2) Put the car in drive or reverse. Hear noise.
3) Pat self on back.

[gl1674]

A little bit of throttle helps to hear the buzzing sounds on my car.
Since two solenoids are supposed to buzz (A and C) the test is not definitive...

[UberRoo]

Originally posted by gl1674
A little bit of throttle helps to hear the buzzing sounds on my car.
Since two solenoids are supposed to buzz (A and C) the test is not definitive...

I have no explanation for why duty solenoid C cycles, while duty solenoid A does not, but this appears to be the case. The test is valid.

In either case, if there is noise without the FWD fuse, and it goes away when you plug it in, that's pretty conclusive.

[SVXRide]

UberRoo,
I'm going to try the "noise" test tonight - with the car in gear! I'll also try the with and without fuse check. Thanks!
-Bill

[SVXRide]

Well, I went out and did the "key "on" and transmission in gear" noise test and was greeted by a stoney silence. I put a 10A fuse in the FWD socket and the FWD icon came on on the dash. I also ran through the diagnostic for the TCU and the POWER light just sat there - lit up and not flashing one bit.
I'm going to see if I can't get the car up on a lift to pull the speed sensor to check for metal shavings and pull the pressure port plug to see if I can't figure out what type of threads it has so I can rig up a fitting to hook a pressure gage to. Does anyone know what size the plug is?
-Bill