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........after any transmission failure, even though the valve bodies rarely receive any physical damage........
Just for you’re viewing pleasure, I remembered the below picture when I made above comment about valve bodies and is why I used the word rarely, because obviously this guys valve body did receive physical damage. I found it again and thought you might like seeing it; obviously not even a rebuild was going to fix that transmission.
Trans problem.jpg
 

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Discussion Starter · #23 ·
Good news! I went out with better lighting and the circuit diagrams from the FSM in hand. I was definitely probing the right pins last time, but I was able to make a better connection this time because it wasn’t 9pm by the light of a flashlight alone. Getting full battery voltage (~12.8v) on C46-25 and C46-12 (blue/red) with the ignition on, and the same on C47-39 (red/black) regardless of ignition on or off.

So, what all this means is it’s possible FAC was mistaken and the computer needed repairs. I’ll be getting it back soon… it got delayed by UPS leaving Texas. In the interest of not causing any new issues I’m going to hold off on further troubleshooting until it’s back in the car. Troubleshooting 101… one variable at a time. Since all signs point to that TCU, I’ll hold out hope everything magically works when I hook it up.


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Discussion Starter · #24 ·
Verdict: no love. Symptoms are unchanged with the new caps. I have to go back through the posts and see if I can wrap my head around it all.

Interestingly, it still behaves differently in Drive and First. In First, it doesn’t even try to engage the proper gear, it just acts like it’s stuck in third. In Drive, it seems to be trying for a split second to move when I first hit the gas, but then it slips and boom, back in third. I’m talking a SPLIT second, to the point where it may be in my imagination.


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Symptoms are unchanged with the new caps. I have to go back through the posts and see if I can wrap my head around it all.
Sorry about capacitors not helping, but at least you don’t have to worry about them anymore.

You completed #1 from my #8 post and checked OK, so to start go back to that post and do solenoids check I outlined in #2 of that post.

Just for reference what is the part# on your TCU?
 

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Discussion Starter · #27 ·
Ok, resistance values…
Pin 1: 3.6
Pins 3 and 4: both 21.3
Ambient temp 77F according to the weather channel.

+12 applied to pin 1 gives me a LOUD click. Pin 3 is quieter, and pin 4 is quieter still. I’m not sure if this indicates a fault with the shift B solenoid, or if it’s location in the transmission just muffled it.


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Below is list of possible causes from troubleshooting guide for these automatics. Strike-thru indicates you've eliminated those. Red text is my comments.

Transaxle Remains In 3rd Gear

* Defective contacts at ignition switch Power to Blue/red wire eliminates this one.

* Defective Damper Clutch Control Solenoid Valve (DCCSV) on valve body or wiring circuit
Tested OK post #32

* Defective end clutch Disassembly required to check but I did question if you noticed a problem with OD :unsure:

* Defective front clutch retainer Disassembly required to check

* Defective front or rear clutch Disassembly required to check

* Defective kickdown band Disassembly required to check

* Defective kickdown servo switch Disassembly required to check

* Defective low-reverse brake Disassembly required to check

* Defective or improperly adjusted inhibitor switch Disassembly required to check

* Defective Pressure Control Solenoid Valve (PCSV) on valve body or wiring circuit
Tested OK post #27

* Defective pulse generators "A" and "B" or wiring circuit Tested OK post #32

* Defective Shift Control Solenoid Valve (SCSV) "A" or "B" on valve body or wiring circuit
Tested OK post #27

* Defective Transaxle Control Unit (TCU) Checked and tested by FAC

* Improper shift cable adjustment

* Low fluid level Assume one of first things checked

* Low line pressure Requires proper gauge set

* Malfunction in valve body Disassembly required to check

* "O" Ring for low-reverse brake circuit not installed
between valve body and transaxle case Disassembly required to check
 

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Ok, resistance values…
Pin 1: 3.6
Pins 3 and 4: both 21.3
Ambient temp 77F according to the weather channel.

+12 applied to pin 1 gives me a LOUD click. Pin 3 is quieter, and pin 4 is quieter still. I’m not sure if this indicates a fault with the shift B solenoid, or if it’s location in the transmission just muffled it.
Pin 1 resistance little above the 3.2 upper range but with 77F temp, I'd say those readings are OK. And yes location of solenoids will make difference in sound of click, even though they're line up in a row. The main thing is a sound means they're engaging with power. I'll update the list with strike-thru.
 

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The pulse generators require an Oscilloscope to test wave pulses, but you could at least do resistance checks I guess. Attached is that test with O-Silly-Scope part left out. It’s same type connector as the solenoid connector; in fact they have been plugged together swapped before when engine/trans reinstall by one other member here.

IIRC from factory the connector was attached to one of support legs of relay box next to air filter. The check ohm readings are taken on device connector side, Black & White wire from pins 1 & 2,…… Red & Green wire from pins 3 & 4.

Edit: The colors I indicated are more than likely harness side of connector. The device side to the pulse generators might be different, since some of device suppliers didn’t always use same color wires as manufacture did and showed in prints. And the more I think about it, I seem to recall wires from pulse generators themselves to the connector had wires colors that almost matched each other, so just read connector pins as indicated.

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* Defective Damper Clutch Control Solenoid Valve (DCCSV) on valve body or wiring circuit
Might check later
Sorry I didn’t have you check TCC solenoid when you were doing the other solenoid checks, but I didn’t think torque converter clutch lock-up solenoid would cause limp mode :unsure:. I also didn’t recognize what the DCCSV listed above was referring too, after some search in electrical prints it appears they’re one in the same, with different terminology in different locations. So you might want to do the TCC solenoid check at pin 2 as you did on other pins. Your model year appears to be 13 ohms.
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Discussion Starter · #32 ·
TCC solenoid: 13.7 ohms, clicks with +12
Pulse generators 255 ohms on A, 257 ohms on B

All within (or close) to spec.


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TCC solenoid: 13.7 ohms, clicks with +12
Pulse generators 255 ohms on A, 257 ohms on B
Yeah those #’s look good, we're quickly running out of possibilities from external standpoint. I assume you checked fluid level early on. That would just leave shift cable adjustment, which I’m not sure how that would have suddenly changed after 4K miles, but will attach that process below, but suspect if you just move shift lever to N (neutral) and check that hole at end of control lever is lined up with hole switch body and nothing is loose, that should be good enough.
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Discussion Starter · #34 · (Edited)
So I may be onto something… while checking the adjustment on my shift cable, I noticed a rapid ticking when I shifted into drive by hand. I never noticed it before because the engine was always running.

On a hunch, I unplugged the solenoid connector - noise went away.

I got back in the car. The noise happens for about a second if I shift into reverse, and happens for about a second, then pauses, then happens continuously forever in any forward gear.

I also checked pins 4 and 6 on the diagnostic connector - code 45 and 47 which stand for open circuit on the PCSV and TCC solenoids.

I haven’t found a smoking gun yet but I think I’m getting there…

Edit… just had a thought… maybe the codes are leftover from when I pulled the plug?


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So I may be onto something… while checking the adjustment on my shift cable, I noticed a rapid ticking when I shifted into drive by hand.
Yep, you’re on to something there for sure. When you say shifted it into drive by hand, do you mean the cable connector was completely lose from the manual control lever and you moved that lever by hand to drive position? If so there’s several possibilities;
1) park/neutral switch not adjusted correctly to control lever when it’s in detent for neutral position.
2) park/neutral switch has internal fault sending more than one signal to TCU when in drive.
3) Problem with connector to park/neutral switch or wiring.
4) There is still a problem with TCU.
5) There’s still possibility of solenoid problem even though resistance and voltage checks (but seems unlikely to me).

First do the complete setup of park/neutral switch as outlined above, take cable completely lose from manual control lever and leave it disconnected until you've run down the problem (it can be reattached and adjusted later when done). Just to be sure you understand what’s happening, there are mechanical detents inside transmission for all positions P thru L, when you position control lever in mechanical detent for N position the park/neutral switch is then set to the control lever by aligning the switch hole to the lever hole by moving switch into position. That assures when control lever is placed in any gear the switch then sends appropriate signal to the TCU, to activate proper solenoids in transmission.

When you complete that setup, if you still hear continuous clicking in transmission when lever set to drive. You can check power input to TCU connector from the park/neutral switch when in drive, to narrow down if problem is from switch or with in TCU. I can help with print reading and wire identification if needed in this step.
 

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Discussion Starter · #36 ·
Have to clarify - I didn’t loosen or disconnect anything related to the shifter. I checked to make sure the holes lined up. They do. Then to make sure it was moving appropriately I moved it by hand by turning the linkage itself into drive. That’s when I heard the rapid clicking/ticking/buzzing from the solenoid.


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Have to clarify - I didn’t loosen or disconnect anything related to the shifter.
OK…. To be sure cable and shift lever is not causing the problem, disconnect it completely from control lever. What that does is allows confirmation that internal detents are aligning the spool valve correctly with selected position and then move control lever by hand back to neutral position N and double check holes with switch still lineup.
 

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Discussion Starter · #38 ·
Let me pivot real quick...

Let's take it for granted that it's unlikely I have two separate faults causing the issue.

My fluid level is a little bit high right now, and may have even been a bit foamy (tough to tell). Is it possible that's messing with the pressure in the hydraulic components and causing shift problems? If so, it might be worth the $25 for some Maxlife @ Wally World and $14 for a filter at O'Reilly to rule that out. Not sure how long it's been high, or if it could be high BECAUSE of a solenoid problem and not be CAUSING the solenoid problem.

How likely is it that FAC was mistaken and the TCU is actually toast? The symptoms are unchanged with the capacitor replacement. Unfortunately our cars are less and less common these days... I've seen two others in my town, one clearly a '97 or '98 VR4; the other looks to be a similar-vintage SL to mine, maybe even an automatic judging by the way it sounded when it passed me while I was walking, but unless the owner is a very kind member of this forum, I doubt I have access to a spare TCU...
 

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Let me pivot real quick...

Let's take it for granted that it's unlikely I have two separate faults causing the issue.
I’m not big on jumping around without first confirming a particular possibility is first ruled out. In this case it’s about if inside lever/cable is placing the trans control lever in proper location when moved. There’s detents for the lever inside of car, which has little impact on transmission operation other than it placing the control lever on trans in perfect location when lever inside lever is moved. All transmission operations requires correct placement of that control lever to trans internal detents and park/neutral switch placement from the inside lever. When you pushed control lever to drive position from under hood, you were pushing against cable and inside lever detent, it’s possible the cable was pushing back and not allowing control lever to completely locate internal detent in trans and park/neutral switch to barley make contact with drive contact inside causing solenoid to drop in and out. If you don’t wish to check setup of those components, at least place transmission in drive from inside the car and turn ignition to ON and go to transmission to see if you still hear solenoid steady clicking (it will be pulling on cable then).
 

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Is it possible that's messing with the pressure in the hydraulic components and causing shift problems? If so, it might be worth the $25 for some Maxlife @ Wally World and $14 for a filter at O'Reilly to rule that out. Not sure how long it's been high, or if it could be high BECAUSE of a solenoid problem and not be CAUSING the solenoid problem.
The fluid level will be high if not checked in neutral and engine running and not to forget it hasn’t been shifting so some passages/clutch packs might not be completely full which would cause a high reading at dipstick. But new fluid and filter couldn’t hurt if the fluid is equivalent to Diamond SP II or better with the friction modifier, but not sure then how you could check fluid level if you can't run it thru all the gears.

How likely is it that FAC was mistaken and the TCU is actually toast? The symptoms are unchanged with the capacitor replacement. Unfortunately our cars are less and less common these days... I've seen two others in my town, one clearly a '97 or '98 VR4; the other looks to be a similar-vintage SL to mine, maybe even an automatic judging by the way it sounded when it passed me while I was walking, but unless the owner is a very kind member of this forum, I doubt I have access to a spare TCU...
Yes its possible FAC was mistaken and TCU still has problem. I was thinking about possibility of trying another TCU when I ask about the part# of yours and wondering what might be available. But you're thinking clearly about some that might be available in your hometown, I was even thinking about any from ’93-’96 as I know those have same pin-outs at the connector. By the way where are you located?
 
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