[Casey]

This morning after starting my van and getting on the road, a new problem has arisen. When I take off from a standing start, the van is lacking a bit of power (almost feels like a brake is dragging- they're not, I made sure). It feels like the van is trying to pull 10,000 pounds of weight. I only drove it 2-3 miles, then headed back home.

After test driving it in my neighborhood, the van doesn't shift out of first gear until you step the throttle down at least 1/2 way, then it quickly upshifts into second, but not harshly. I would say it upshifted too early, if anything. It's hard to say as I don't want to push it too hard and make anything worse.

I replaced the O2 sensor this morning as I got a "13" SES code and the SES light came on yesterday, but replacing it didn't change anything, other than eliminating the 13 code.

I've never had any trans issues since I bought it in March. Trans fluid level is correct. Fluid and filter were both changed two months ago with the correct DexMerc fluid. No signs of overheating, no hard shifting- no sign of bad things to come.

I read about the 1-2 shift solenoid issues, but I'm not sure if this qualifies, as there's no hard shifting.

I had the TC unbolted Sunday when I was searching for a persistent rattle, and now I'm wondering if I didn't index it properly. I marked it before I removed the three bolts, but I can't honestly remember if I matched it up again when I bolted it back to the flexplate. Does it have to be re-attached the way it was positioned before I unbolted it, or does it not matter?

Suggestions welcome.

 

[Casey]

I was just under the van looking for leaks or anything obvious and found an open-ended rubber hose (5/16" OD or so) coming from the top side of the trans, about even with the pass. side cooler lines, and just to the pass. side of longitudinal center. Is this just a vent or should this line be connected to something?

 

[Big_kid]

The torque converter does not need to be indexed to the flex plate. The hose sounds like it's a vent, but I'm not 100% positive. I've not looked at mine that closely yet.

 

[rev_les]

This sounds crazy, but it happens.... check your fuel pressure.Low pressure from a pump that's on it's way out will cause all kinds of odd problems, including making them shift incorrectly, like the transmission is having problems.Good luck!

 

[Casey]

The engine revs just fine in neutral and park, and performs fine in reverse, so I don't think this is an engine issue. The trans feels sluggish to engage, almost like the TC is slipping.

 

[Casey]

Someone on another forum mentioned it might be the forward clutch slipping. Is there any way to check this without a tear down? In the '90 FSM It looks like the forward clutch is near the top of the trans. If I remove th evalve body can I see/remove the forward clutch?

Also, I've read a online about this common issue of valve failure in the 4L60E:

"The pressure regulator boost valve and it's sleeve should be replaced every 40,000 miles to avoid major damage that occurs when accumulated wear in the boost sleeve causes insufficient pressure to be made available in reverse. We are seeing too many major repairs of the 4L60E at around 50,000 plus miles being traced to this boost valve and sleeve. The valve and sleeve can be replaced easily during a routine service of the transmission at an additional cost of around $50.00. This should be considered a must do maintenance procedure on the 4L60E."

 

[Casey]

Found the answer online, not worth the trouble of swapping tailshafts.

 

[astro355]

Why would you have to swap tailshafts?

If the forward clutch is slipping, there would have been (or would have now) some friction material in the tranny fluid. I'm assuming that it was a pretty red color before (or currently is now).

 

[Casey]

Why would you have to swap tailshafts?

Different tailshaft lengths between the 4/AWD 4L60E and 2WD 4L60E.

If the forward clutch is slipping, there would have been (or would have now) some friction material in the tranny fluid. I'm assuming that it was a pretty red color before (or currently is now).

The trans is toast. There was a little bit of very fine powdered metal stuck to the magnet when I changed the fluid and filter, two months ago, but but no small metal chunks at all. I'm pulling the trans tonight regardless- it barely made it home from the trans shop this morning at it was a two-mile drive at most. :doh:

 

[Casey]

I finally got the trans rebuilt, and after setting the forward clutch pack clearance too tight, it's back in for the second time, and this time it acts properly in all gear positions. With the too-tight fwd clutch pack clearance, it wanted to move forward no matter which gear (or park, or neautral) was selected. The teardown confirmed the diagnosis, so that's been fixed.

The original trans discs and steels were badly burned (fluid and filter were near-new), so whatever caused the issue in DRIVE is still present and I have no desire to burn up all the clutch packs trying to ID the issue via test drives.

I've been talking with Dana @ Pro Built Automatics (which is where I got the excellent rebuild kit from) and he's been very helpful, but I still have the same issue which signalled the start of problems to come. When I select DRIVE (ie. OD on the shift indicator) and step on the gas, there is an obvious delay between throttle application and vehicle movement. After talking with Dana and the person at the trans repair shop, I'm thinking it's probably not starting out in first gear, but rather second or third gear. My best description was that it felt like the van was trying to pull a 20,000 lb trailer or the brakes were dragging (they aren't), and Dana confirmed that IF it is starting out in second or third gear, it will feel like what I described. When I manually select first gear (1 on the shift indicator), the van will move normally with the 'delay', so I don't think this is a fuel issue for that reason alone.

I replaced both the 1-2 and 2-3 shift soleniods with new parts when I re-installed the valve body, but the symptom is still the same.

I've grounded out the "B" terminal as described here: http://www.troublecodes.net/GM/ , but the only SES code that flashes is the "12" code over and over. I did have a bad O2 sensor (13 code) right after the trans issue starrted, so I replaced the O2 sensor with a new Bosch unit and the SES light and 13 gone are gone now....just the 12 over and over.

Is there a way to check for any other codes that may be present and wouldn't flash with the ground out method? This is a '95 with the OBD I system, so if I can pick up a $25 scanner and it will show other codes, I would do that. If I need to take it to the shop down the road and have themn plug in the $300 scan tool, I'll do that. I'm not familiar enough with the different years and which scan tools give you what information, if there even are any codes to be read on my van.

TIA for any advice. :banana:

 

[Matrixx]

Hi Casey

Thanks for the update. Their is some information on scan tool types in the old forum. We talked about this a few different times with the OBD I and OBD II sytems.

Scan Tool Search Result:
http://archives.astrosafari.com/ikonboa ... 0055152506

Scanner Search Result:
http://archives.astrosafari.com/ikonboa ... 6757ca6186
http://archives.astrosafari.com/ikonboa ... l=scanners
http://archives.astrosafari.com/ikonboa ... l=scanners

Code Reader Search Result:
http://archives.astrosafari.com/ikonboa ... da5b5ff207

Hope something here helps.

 

[Casey]

I disconnected the wiring harness plug to the trans and tested both pink wires with the ignition switch in the ON position, and I had 12V and 6V of power, so at least the trans is getting power from the ignition switch, and a bad ignition switch is throwing the trans into limp mode.

I fired up the van briefly this morning and vverify the problem was still there (it is), but some SES codes finally came up:

59 - Transmission Temperature Sensor Circuit (Low Temp)
67 - Torque Converter Clutch (TCC) Solenoid Circuit Fault
82 - 1-2 Shift Solenoid Circuit Fault

The pressure switch which contains the temp sensor and the TCC solenoid are both original pieces and haven't been replaced. I replaced both the 1-2 and 2-3 shift solenoids with new parts two days ago.

Since all three are a circuit problem and all share the same wiring harness, I might try swapping the harness from the '94 parts trans I bought and see if anything changes. Should I just get a multimeter and start checking resistances and voltages for each part at the valve body? Does this sound like a common ground issue? Is the appearnce of all three of these codes indcative of a known problem (i.e., bad PCM, bad ignition switch, bad pressure switch, etc.)?

If I have it put on an engine/trans scanner at a shop, will that scanner be able to pull any additional codes and/or be able to pinpoint the problem? I don't want to have it towed to a shop only to have them tell me the trouble codes I already found are all they're getting. :x

Is there a repair flow chart which shows what to check and repair for each code?