Toyota Nation Forum banner
1 - 20 of 34 Posts

·
Registered
Joined
·
18 Posts
Discussion Starter · #1 ·
I'm new to posting here but I hope I'm in the right place. About once every 3 days the vehicle, an automatic, will shift from 1st to 3rd.
If you let off the gas and reapply it will engage 2nd. You can also manually shift it to second. I'm unable to establish any common circumstances like weather or bumpy roads. Only once did I get a 62 code on the od light.
Things I've tried so far
1. Replaced shift solenoids with aftermarket.
2. Replaced shift solenoids with junk yard originals
3.replaced speedo cluster after hearing about issues with analog signal.
Inspected harness from ecm to solenoids.
4. Checked for high resistance of solenoid harness.
And now I'm looking at the ecm. I've read about issues with bad capacitors on later model camry and lexus ecms. Does anyone know if this is common to the gen 7 corolla.
It's my daughters car, otherwise I would likely drive it as is. Thanks in advance for any input on something I may have overlooked.
 

·
Registered
1995 Toyota Corolla
Joined
·
2,018 Posts
I changed the capacitors on my '95 ECM, but the old ones tested good. Another user here, @Chris94, had issues with capacitor leaking on his '97 but they manifested as engine running problems, not transmission.

Have you bench tested the solenoids? Does the speedometer work correctly? Fluid ok?
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #3 ·
Yes, bench tested all 3 solenoids. All 9 if you include the aftermarket ones and junkyard ones. Old speedo and junk yard replacement work fine. Guess I'll try to find an ecm next . Then I won't be afraid to start experimenting with the capacitors.
Kind of a tough call. It's a pretty clean car with about 138000 miles. Don't want the daughter to be unsafe in it when pulling out into traffic. Don't want to sell it without informing buyer about the issue which naturally would diminish the value. Maybe the tranny is on its way out but hard to imagine with the low miles and no slippage of any kind. Fluid looked like new.
Thanks for your response.
 

·
Premium Member
1994 Corolla DX
Joined
·
4,824 Posts
Sounds like you've hit all the usual suspects so far. I also assume then when you checked ATF levels (which obviously you must have if you dropped the pan to replace the solenoids twice) you did check them with the car at level ground, engine fully warmed up and still running as the fluid needs to be measured when it's actively circulating. I know it seems a bit off-putting to ask someone who has done such advanced work such a basic question, but sometimes we all make silly mistakes :) Similarly I also assume you used a Dexron III/IV (or backwards-compatible VI) fluid.

I'd have to check the troubleshooting section of the A245E in my factory service manual to see if there's anything else that should be checked. I know the shift algorithm relies on a few sensors (other than just the VSS) to trigger shifts - I believe it includes RPM signal and TPS signal.

Speaking of factory service manuals - you should pick one up yourself off eBay - I've found it invaluable to a lot of the work I do.
 

·
Registered
1995 Toyota Corolla
Joined
·
2,018 Posts
I agree, good job narrowing down. DTC 62 is directly about the solenoid.

How's the solenoid connection? I'm not too familiar with the electronic transmission in these cars, is the wiring harness accessible to test?

Here is my writeup for changing capacitors on my ECM FYI.
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #6 ·
Thanks for weighing in Rolla dad. I've read a number of your post and was hoping you might share your knowledge on this issue.
I was indeed very fussy about the correct fluid and level. I also checked the the adjustment on the TPS, several months ago when this first started. Interestingly enough, I have yet to examine the VSS. I'm glad you mentioned it. I located it this evening on top of the transmission near the firewall in the center of the engine bay. They aren't too expensive. I think I'll try that this weekend if I can get the car off of the daughter.
Intermittent problems are hard to find. It's much simpler when they stay broke. It has forced me into the dive bombing method of trouble shooting. Not a fan. I also pulled the ecm again to look at the internal components. It looked brand new from a visual perspective. I'll probably still swop it out if I don't have any success with the VSS. And yes, gonna get a hold of a shop manual.
Thanks again for responding. I'll let you know how it progesses.
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #7 ·
Also a great write up on replacing the ecm capacitors. I share your enthusiasm for aquiring a spare beforehand. Which numbers on the ecm label are most critical for a workable replacement? Or did you just match engine and transmission? Thanks for sharing your write up Apples.
Font Gas Bumper Automotive tire Rectangle
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #8 ·
Very informative. I did test the harness from the ecm to the solenoids or shall I say the plug leading into the transmission. Since the problem is so intermittent I'm guessing the circuit would test good unless I happen to catch it at the precise moment of failure.
Your right about getting that ecu liberated from its tomb. Very much a pain.
Thanks again apples.
 

·
Registered
1995 Toyota Corolla
Joined
·
2,018 Posts
For my spare, I got the same part number as the original. For you it would be 89661-02150.

If you recap it, be certain to use the appropriate type and manufacturer series of capacitor as I mentioned in my thread.
 

·
Registered
1997 Corolla
Joined
·
5,606 Posts
The electrolytic capacitors in the ECU may not look bad. You would need to test them either out of circuit with a capacitor tester or in circuit with an ESR meter. If you were going to remove them to test you might as well replace them. Swapping another ECU to test might be easier if you can find a cheap one.

These factory repair manuals are a little cheaper than I usually see them for.
The wiring diagram is separate.
 

·
Premium Member
1994 Corolla DX
Joined
·
4,824 Posts
Ok so I was reviewing the FSM for A245E. It's not apparent they have an immediate symptom match for 1-->3 (skipping 2) but the closest symptom I could find is "no up-shift 1-->2".

The troubleshooting is divided into three sections:

1. Electronic
2. On-vehicle repair
3. Off-vehicle repair

And the FSM suggests the issues are tackled in that order. So assuming the "no 1-->2 upshift" is the closest symptom match it suggests the following priority order, some of which you've arguably already ruled out:

Electronic:
1. No 1 / No 2 Solenoid Circuit
2. TPS sensor circuit
3. VSS circuit
4. On-vehicle repair chart (see next section)
5. PNP switch
6. Off-vehicle repair chart (see last section)
7. ECM

On-vehicle repair
1. 1-2 shift valve (which brings up an interesting point - perhaps you should try to swap the valve body, not just the solenoids)
2. No 1 solenoid
3. No 2 solenoid
4. Off-vehicle repair chart

Off-vehicle repair
1. Second brake
2. No 1 one-way clutch

I guess the takeaway I'd have is valve body is higher on the list of prioritized areas than the ECM. Now that doesn't mean the ECM capacitors couldn't be at fault but just in terms of how you might want to go about it. The age of the electronics might throw off this prioritization I guess....
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #12 ·
So, I ordered the replacement ecm after reading Apples last post. I appreciate the info. As I'm sitting in my work truck waiting for the rain to stop, I decide to closely examine the photos I took of the ecm interior components. Low and behold, this particular capacitor does indeed appear to be damaged. Never would have saw it without blowing up the image. Notice the hole with a burnt perimeter. Just as Dr z stated, the quick visual inspection would only reveal the blatantly obvious. Maybe when I get a good schematic, I can determine if that damaged capacitor is directly related to the solenoids. I know that capacitors can become less efficient when they are about to crap out. I recently repaired an old washing machine. The capacitor wasn't delivering enough energy to start the motor. It was intermiitant for a while. Can't help wondering if this capacitor lacks the energy to engage the solenoid.
Sorry for the rambling. Excited about a possible break through
Sleeve Electric blue Asphalt Water Circle
Photograph Product Motor vehicle Automotive tire Font

Ok so I was reviewing the FSM for A245E. It's not apparent they have an immediate symptom match for 1-->3 (skipping 2) but the closest symptom I could find is "no up-shift 1-->2".

The troubleshooting is divided into three sections:

1. Electronic
2. On-vehicle repair
3. Off-vehicle repair

And the FSM suggests the issues are tackled in that order. So assuming the "no 1-->2 upshift" is the closest symptom match it suggests the following priority order, some of which you've arguably already ruled out:

Electronic:
1. No 1 / No 2 Solenoid Circuit
2. TPS sensor circuit
3. VSS circuit
4. On-vehicle repair chart (see next section)
5. PNP switch
6. Off-vehicle repair chart (see last section)
7. ECM

On-vehicle repair
1. 1-2 shift valve (which brings up an interesting point - perhaps you should try to swap the valve body, not just the solenoids)
2. No 1 solenoid
3. No 2 solenoid
4. Off-vehicle repair chart

Off-vehicle repair
1. Second brake
2. No 1 one-way clutch

I guess the takeaway I'd have is valve body is higher on the list of prioritized areas than the ECM. Now that doesn't mean the ECM capacitors couldn't be at fault but just in terms of how you might want to go about it. The age of the electronics might throw off this prioritization I guess....

Really appreciate your research. I'm already knee deep into the ecm but certainly will be revisiting the TPS and checking the VSS . I haven't looked into the valve body issue yet. I'll need to review a procedure for accessing the valve bodys. Hopefully won't have to remove the transmission. It is certainly plausible that a sticky valve or restricted passage could cause my issue . I'm guessing the pnp switch is the park neutral sw? , I did clean it and check it with a meter shortly after the issue began. I really need to get that shop manual. Could have purchased several vs the time and money I've already spent. Sincerely grateful for the advise.
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #15 ·
It sure looks flakey in the picture. Just waiting on temp ecm to arrive. Going to look at it with a jewelers loop when I home. I'll keep you up dated and will definitely be using your write up to order replacement caps. Great resource.
 

·
Registered
1997 Corolla
Joined
·
5,606 Posts
I can't tell exactly how it looks damaged. I see it's discolored and maybe bulging a little? As these electrolytic capacitors get old the internal resistance increases which causes them to heat up more which can make them expand. The extra heat causes them to dry out even more and stop working.

I took the valve body off my 3-speed on my 1990 Corolla earlier in the year, and I can say that there really isn't much to break or wear out inside a valve body, so I would only go down that route as a last resort after checking/swapping the ECU. I thought maybe there could be a broken spring in my valve body because of some shifting problems, but every part was intact, and there was no dirt or any sort of built up gunk to cause problems.
 

·
Registered
Joined
·
18 Posts
Discussion Starter · #18 ·
Yes, the valve body job doesn't look like much fun, considering I've had the pan off twice already. Although the repair manuals are generally spot on with the trouble shooting sequence , I'm hoping to get lucky on the electrical side of it. As Rolla dad mentioned, maybe the age of the vehicle could supercede the normal trouble sequence a bit.
I re examined the capacitor with a jewelers loupe. What looked like a hole in the photo turned out to be only a blemish. Understanding there may still be an issue with the ecm, I ordered one yesterday to have an operating spare before I experiment with the caps on my original. Trying not to throw to much at it at once so as to know what actually resolves the issue. The ecm is next, followed by a VSS (not very expensive or difficult ) then to revisit the TPS. The frustration is that after I have changed a component or made an adjustment, I wouldn't know for a while if it was effective since the issue only occurs maybe once every few days. I thought it was solved a few times only to reappear days later. On a philosophical note; it's like having a wife that's usually great but will randomly act up every now and then for no obvious reason. Yet we pursue the object of our affection with renewed vigor. ... I must be losing it!
Anyway I'll continue on as sort of enjoy the challenge and give updates as I progress. Once again, this community has been great.
Very thankful.
 

·
Registered
1995 Toyota Corolla
Joined
·
2,018 Posts
I can't tell exactly how it looks damaged. I see it's discolored and maybe bulging a little? As these electrolytic capacitors get old the internal resistance increases which causes them to heat up more which can make them expand. The extra heat causes them to dry out even more and stop working.

I took the valve body off my 3-speed on my 1990 Corolla earlier in the year, and I can say that there really isn't much to break or wear out inside a valve body, so I would only go down that route as a last resort after checking/swapping the ECU. I thought maybe there could be a broken spring in my valve body because of some shifting problems, but every part was intact, and there was no dirt or any sort of built up gunk to cause problems.
It looked like there was a hole with a mark around it above the lower 4, but it may have just been a reflection.

If the capacitors look ok, I don't think they're the reason for this problem. The ECM circuit board is multi-layered and complex, and a bad capacitor would cause other issues than just an intermittent shifting issue would be my guess. Chris didn't have a check engine light at all and random stalling (probably ECM shutoff/restart).

This sounds like a wiring issue due to the intermittent nature.
 

·
Registered
1997 Corolla
Joined
·
6,181 Posts
When inspecting capacitors, look for leaking, and swelling/bulging. Any one of those is bad.
 
1 - 20 of 34 Posts
Top