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#21
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A/T skipping 1st gear
"jim beam" > wrote:
> the clutch packs only slip during the actual shift. after that, any > differential is taken up by the torque converter. Thanks, that's reassuring. One thing that still bugs me is why I smelled that burn odor when I got home with my car. It must have come from somewhere under the hood. DB |
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#22
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A/T skipping 1st gear
Dabbler wrote:
> One thing that still bugs me is why I > smelled that burn odor when I got home with my car. It must have come > from somewhere under the hood. Dragging brakes. Dripping oil on some hot engine part. Belt slipping. Belt rubbing against something. Are the motor mounts intact? Did it happen one time only? If it happens again note the conditions. Temperature, humidity, travel on an inclined surface (which will shift the engine on the mounts), heavy load, recent average speed. -- Chuck |
#23
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A/T skipping 1st gear
"Charles" > wrote:
> Dabbler wrote: >> One thing that still bugs me is why I >> smelled that burn odor when I got home with my car. It must have come >> from somewhere under the hood. > > Dragging brakes. Dripping oil on some hot engine part. Belt slipping. > Belt rubbing against something. Are the motor mounts intact? > > Did it happen one time only? If it happens again note the conditions. > Temperature, humidity, travel on an inclined surface (which will shift > the engine on the mounts), heavy load, recent average speed. It only happened that one time. However, the original problem reappeared again last night despite the replaced shift control solenoid. The #4 gear indicator started flashing after a short stop at an ATM machine. Luckily, this time I knew to try to switch into gear 2 to get the car going without all that torque converter work to get some speed. The problem seemed to have disappeared after a longer stop, just like the first time. I wonder what it is with short stops that cause this problem. It might be an indication of a more serious problem developing and I would like to prevent it without spending another $300+ for the wrong medicine. Any ideas? DB |
#24
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A/T skipping 1st gear
Dabbler wrote:
> ...the original problem > reappeared again last night despite the replaced shift control > solenoid. The #4 gear indicator started flashing after a short stop > at an ATM machine. That car just wants some cash from the machine. > Luckily, this time I knew to try to switch into > gear 2 to get the car going without all that torque converter work to > get some speed. That's probably unnecessary. The transmission control computer limits you to second and fourth gears only when in "limp home" mode. > The problem seemed to have disappeared after a longer > stop, just like the first time. > I wonder what it is with short stops > that cause this problem. It could be some heat build-up causing the problem. > It might be an indication of a more serious > problem developing and I would like to prevent it without spending > another $300+ for the wrong medicine. Did the $300 result in the actual change of the shift control solenoid assembly? Did you get the old part? Let's assume that a new solenoid was actually installed. I recall that you have the service manual. Can you read the transmission control unit error codes without a service tool. At least on older models you just watch the flashing lamp on the TCU itself. If so, what error code is flashing now? Still an eight as before? The TCU itself may be failing or it could be a problem in the wiring. A short to battery voltage, an open circuit, a low resistance to ground or an adjacent circuit will register in the TCU and store an error code. The TCU does not differentiate among various conditions. If any anomaly pops up in the shift control solenoid B circuit for instance, the TCU lamp flashes 8 times. Some oil leaks into the connector in the engine compartment and the technician leaps to the conclusion that the solenoid must be changed. As Tom and Ray will tell you, he had a boat payment due. -- Chuck |
#25
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A/T skipping 1st gear
"Charles" > wrote:
> That car just wants some cash from the machine. Maybe just my service technician. > That's probably unnecessary. The transmission control computer limits > you to second and fourth gears only when in "limp home" mode. Well, as I wrote before, when in city with speed limits 35 or under, I like to drive with the AT gear in D3 position but in this case all I got was the torque converter acting like a slipping MT clutch. It was obviously not engaging the 1st gear. Same in D4 position. I was able to start almost normally with the shift lever in D2 position. > It could be some heat build-up causing the problem. I doubt it because I operated the car for only a few miles before the incident and it was night time. Then I drove another couple miles to a restaurant where I spent about an hour and after that the symptom was gone and still is gone. So this issue seems to be transient. The only common thing between the two similar episodes was the short stop. > Did the $300 result in the actual change of the shift control solenoid > assembly? Did you get the old part? Oh yes, I explicitly asked for it and could tell the Honda dealership's technician installed a new one. > Let's assume that a new solenoid was actually installed. I recall that > you have the service manual. Can you read the transmission control > unit error codes without a service tool. At least on older models you > just watch the flashing lamp on the TCU itself. If so, what error code > is flashing now? Still an eight as before? According to the Service Manual, reading the code requires a special tool to read the code which I don't have. I'm assuming though that it would be the same code again as all the symptoms were the same. That also means that they made me pay for the solenoid needlessly and the problem may be somewhere else. > The TCU itself may be failing or it could be a problem in the wiring. > A short to battery voltage, an open circuit, a low resistance to > ground or an adjacent circuit will register in the TCU and store an > error code. The TCU does not differentiate among various conditions. > If any anomaly pops up in the shift control solenoid B circuit for > instance, the TCU lamp flashes 8 times. Some oil leaks into the > connector in the engine compartment and the technician leaps to the > conclusion that the solenoid must be changed. As Tom and Ray will tell > you, he had a boat payment due. I think you might be right here though I doubt the technician gets some extra pay from the dealer employer for this. It's more likely that he just chose the easy way out while at the same time pleasing his boss for the extra billing he generated. Though some of you guys have been singing the praises of authorized Honda service shops, I've had nothing but expensive disappointments with them. I think I should have gone to my independent mechanic as before, but because he could not take on my car right away, I though I would give another try to a Honda service shop. What an expensive mistake that was! It reminds me the case of a former co-worker of mine with a Honda Odyssey problem. The power door motor started behaving erratically and the Honda shop diagnosed it as needing a new servo motor. That costed him some $500 and for a while the problems disappeared. Then the same problem came back even with the new servo. He took it back to the same shop where another mechanic found the problem being some loose ground or something like that. When my colleague remarked that perhaps that was the problem before the motor was replaced, they just shrugged their shoulder by saying that "not necessarily." I have a feeling that's the treatment I would get if I took back my car to them now. I hope my car will be OK till my upcoming scheduled maintenance with my independent mechanic and then let him do his own checking. DB |
#26
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A/T skipping 1st gear
Dabbler wrote:
> Well, as I wrote before, when in city with speed limits 35 or under, I > like to drive with the AT gear in D3 position but in this case all I > got was the torque converter acting like a slipping MT clutch. It was > obviously not engaging the 1st gear. Same in D4 position. I was able > to start almost normally with the shift lever in D2 position. It sounds as though the transmission is getting erroneous signals from the computer. That could be a problem in the wiring or, less likely, the computer itself. I would pull the connectors off at the TCU and, using an ohmmeter, check the wiring. The troubleshooting procedure is in the service manual. Concentrate on measuring the solenoid resistance. You'll probably see high resistance readings where you would expect to see the low resistance reading of each solenoid. Then you disconnect the solenoid connector at the transmission and take another set of readings. If those resistances are correct, the problem is in the wiring between the solenoid connector and the computer. If not, one or more solenoids are defective. There are probably four solenoids to check, two shift control and two lockup. If you still have the old solenoids, measure their resistance. If they are okay the resistance will be in the range of 12 to 24 ohms. If they measure several hundred ohms or higher, they were truly bad. I went so far as to connect LEDs to the solenoid lines of my TCU to verify that the correct signals were coming out of the computer while I drove. You might even invest in the tool to read the diagnostic codes. -- Chuck |
#27
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A/T skipping 1st gear
"Charles" > wrote:
> It sounds as though the transmission is getting erroneous signals from > the computer. That could be a problem in the wiring or, less likely, > the computer itself. I would pull the connectors off at the TCU and, > using an ohmmeter, check the wiring. The troubleshooting procedure is > in the service manual. Concentrate on measuring the solenoid > resistance. > > You'll probably see high resistance readings where you would expect to > see the low resistance reading of each solenoid. Then you disconnect > the solenoid connector at the transmission and take another set of > readings. If those resistances are correct, the problem is in the > wiring between the solenoid connector and the computer. If not, one or > more solenoids are defective. There are probably four solenoids to > check, two shift control and two lockup. I don't see how this could yield any results with a transient problem as this seems to be. Right now all is well and who knows when the problem manifests itself again. That would be the time to carry out the thing you suggest but I may not be in a situation when I could do it. > If you still have the old solenoids, measure their resistance. If they > are okay the resistance will be in the range of 12 to 24 ohms. If they > measure several hundred ohms or higher, they were truly bad. This I can do now and will report back on it later. > I went so far as to connect LEDs to the solenoid lines of my TCU to > verify that the correct signals were coming out of the computer while > I drove. Great idea. > You might even invest in the tool to read the diagnostic codes. Well, I don't think I will keep this car long enough to make it worthwhile. It just occurred to me: what if the problem is in the lock-up control solenoid instead? Just what is the function of the lock-up control solenoid? DB |
#28
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A/T skipping 1st gear
Dabbler wrote:
> I don't see how this could yield any results with a transient problem > as this seems to be. The condition may not be transient even while the indication _is_ transient. You may be on either side of the threshold of a failure indication. I had the same intermittent indications when my lockup solenoids were going bad. They got worse with heat but the resistance readings of the failing coils was always high. When they got hot the current draw changed enough for the TCU to register a problem. Last week my TCU was flashing a #8 code. I previously found a bad connection at the TCU. At that time I opted not to dismantle the connector and risk breaking a wire. I simply reseated the pin in the connector. The problem disappeared. When it reappeared last week I pulled back the carpet, grabbed the cable bundle and moved it around a bit. The flashing indicator on the dash didn't reappear so I pulled the fuse to reset the TCU lamp and went whistling past the graveyard. I diagnosed the problem with an ohmmeter even though the dash indicator wasn't always flashing. Bad lockup solenoids or associated wiring lead to funky shifts and rpm flares. -- Chuck |
#29
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A/T skipping 1st gear
"Charles" > wrote:
> The condition may not be transient even while the indication _is_ > transient. You may be on either side of the threshold of a failure > indication. I had the same intermittent indications when my lockup > solenoids were going bad. They got worse with heat but the resistance > readings of the failing coils was always high. When they got hot the > current draw changed enough for the TCU to register a problem. OK, I measured the resistance between the connectors of the old solenoid: it was 30 ohms. I guess it's a bit too high, right? > Last week my TCU was flashing a #8 code. I previously found a bad > connection at the TCU. At that time I opted not to dismantle the > connector and risk breaking a wire. I simply reseated the pin in the > connector. The problem disappeared. When it reappeared last week I > pulled back the carpet, grabbed the cable bundle and moved it around a > bit. The flashing indicator on the dash didn't reappear so I pulled > the fuse to reset the TCU lamp and went whistling past the graveyard. > > I diagnosed the problem with an ohmmeter even though the dash > indicator wasn't always flashing. Thanks for the tip. I'll see what I could do though I am a bit hesitant to screw around with the TCU. > Bad lockup solenoids or associated wiring lead to funky shifts and rpm > flares. Good to know. At least when I experience those symptoms I will know where to start looking. Thanks again, Dan |
#30
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A/T skipping 1st gear
Dabbler wrote:
> OK, I measured the resistance between the connectors of the old > solenoid: it was 30 ohms. I guess it's a bit too high, right? No, that's probably within limits. Apparently they replaced a good solenoid assembly. Sorry. What is the accuracy of your ohmmeter? The range of acceptable values for my old '88 Prelude transmission is 12 to 24 ohms. When my solenoid went bad both coils measured about 900 ohms. Does your Accord service manual give the tolerance? (It may be buried in the troubleshooting chart.) At the low end of the range, your ohmmeter may be off. I wouldn't worry about 30 ohms. I _would_ be concerned if it was 300 ohms. The next question is, what are the resistance readings of the solenoids in the vehicle? The TCUs are solid. They have a lot of protection circuitry and they have to withstand some wild temperature swings. The circuit board components are encapsulated. You'll have a hard time killing it. The external wiring is the weak link in the system. -- Chuck |
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