Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
|
|||
|
|||
97 Blazer 4X4 ECT problem
Hi;
Code said TCC or circuit. The original TCC solenoid was found with crumbling electrical connections. Ran good for one night after it was replaced. The only way it can know for sure if the TCC is bad or not engaging is to compare the VSS to the crank sensor. If someone could confirm or deny this I'd appreciate it, when it threw the code and started taking off in second, with passing gear disabled, this is a "limp home" mode, correct ? I ask because it's showing exactly the same symptom. What is the likelyhood that it needs a torque convertor clutch ? I'll mess with valve bodies and bands, even pumps, but I will not take a torque converter apart, even for my Mother. The rebuilt is $360 I guess and we got guys to put it in. Also, what else to check before taking the plunge. Thanks in advance for any help. JURB |
#2
|
|||
|
|||
JURB6006 wrote: Hi; Code said TCC or circuit. The original TCC solenoid was found with crumbling electrical connections. Ran good for one night after it was replaced. The only way it can know for sure if the TCC is bad or not engaging is to compare the VSS to the crank sensor. If someone could confirm or deny this I'd appreciate it, when it threw the code and started taking off in second, with passing gear disabled, this is a "limp home" mode, correct ? I ask because it's showing exactly the same symptom. What is the likelyhood that it needs a torque convertor clutch ? I'll mess with valve bodies and bands, even pumps, but I will not take a torque converter apart, even for my Mother. The rebuilt is $360 I guess and we got guys to put it in. Also, what else to check before taking the plunge. Thanks in advance for any help. JURB ah, what do you have? The notorious P1870 code? I have similar problems with mine when its hot on the hiway. Otherwise, its fine. What i have discovered is that the valve body wear is causing problems. The valve hangs up in the valve bore and the TCC does not fully lock up. New valve bodies are pretty expensive. A company called Sonax makes kits and valves to repair the valve body without changing it. There is a special reamer and a updated valve to salvage the body. You might check it out. I have been trying to figure out if i can take the body off and repair mine with the trannie still in the truck. I take it you have a 4l60E? If its gone too long slipping, you may need a rebuilt torque convertor also. Bob ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#3
|
|||
|
|||
What i have discovered is that the valve body
wear is causing problems Thanks for the info, but I hope you're wrong. I understand that clutches don't like it when they are anything but completely engaged or disengaged. Thing is, like I said the electrical connector wasn't in too good of shape and I'm hoping the A. we don't have the valve body problem and B that doesn't need a torque convertor. One hopeful sign, I believe is here a href="http://member.aol.com/JURB6006/trans01.jpgPicture of connector piece (click here)/a Now the way I see it an intermittent connection could cause it, but the pins are clean, and it doesn't look like it is supposed to switch to a lower holding current, so why the burnt area ? My guess is the connection started going bad, then heat from that caused it. Could the coil have shorted turns ? if so I might need to try to find the transistor in the computer that drives it, it may be bad, thermally. While I'm hoping for the best, I want to be ready for the worst. Thanks for the info on the valve body, and if the torque convertor winds up getting replace I see to it that this is looked into, don't want to burn up another one. Do you happen to know how to check for sure if it has the problem with the valve body ? We have micrometers and all kinds of machinist tools and measuring instruments, and know how to use them. Is there a telltale step in the bore or is it just wear with a smaller section of the valve piston cocking ? Thanks again, for now I'm still on it. JURB |
#4
|
|||
|
|||
Sorry;
a href="http://members.aol.com/JURB6006/trans01.jpg"This is the good link./a href JURB |
#5
|
|||
|
|||
JURB6006 wrote: Sorry; a href="http://members.aol.com/JURB6006/trans01.jpg"This is the good link./a href JURB http://www.transmissionspecialty.com...7754-Combo.htm http://www.transmissionspecialty.com...arts/77805.htm http://www.transmissionspecialty.com.../77754-09K.htm http://www.transmissionspecialty.com/tech_all.htm Bob ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#6
|
|||
|
|||
HI, and thanks for the input;
So far so good, but now the question becomes, is there a definitive way to see if this valve body has that problem ? Feeler guage ? The thing is, being prepared for the worst but hoping for the best I can now see the possibility that the valve body is defective, and the if a new torque convertor is installed this problem could definitely cause it's premature failure. For now we can't tell whether the TCC is really fried or if it's an apply problem. Also I have some additional info, the actual codes are (P) 740, 753 and 785. With any luck, this might shed some light maybe ? This is one fault (I THINK), and to have three codes. . . . The problem is I don't have a model specific book for this, up until now I've only been told the descriptions for the codes. Of course one will be TCC or circuit, and then I suspect one of them will be tranny fluid temperature, but what about the other one ? Incidentally I did check the web resources pointed out, they were quite informative, except for one thing. How to tell if this is the problem. Hell it could be the computer, but to find that out I'd have to reset it and make it go to where it locks the TCC. Whether the solenoid is driven is one piece of info. You may have seen the burnt connector, what if the coil had shorted turns ? If so I might need a transistor in the computer. Are these things even marginally servicable or am I going to be looking at an encapsulated assembly ? (like an old tripler in a TV) It would be a real (_|_) kicker to do all this torque convertor and **** and find out all I needed was an ECG375. While I can check a wire for high or low state, I doubt there is a pressure tap for this particular mode. However, does the signal, or maybe line pressure drop when it tries to apply ? Anyone know ? Thank you all again for everything so far,and thanks in advance for whatever comes next. The main thing to me is that I don't want to burn up a new torque convertor. JURB |
#7
|
|||
|
|||
JURB6006 wrote: HI, and thanks for the input; So far so good, but now the question becomes, is there a definitive way to see if this valve body has that problem ? Feeler guage ? The thing is, being prepared for the worst but hoping for the best I can now see the possibility that the valve body is defective, and the if a new torque convertor is installed this problem could definitely cause it's premature failure. For now we can't tell whether the TCC is really fried or if it's an apply problem. Also I have some additional info, the actual codes are (P) 740, tcc enable solenoid. 753 1-2 shift solenoid valve 785. 3-2 shift solenoid With multiple codes for solenoid problems, i would be looking at a plug or wire harness problem first. Did you unhook the transmission harness plug and inspect the pins? Maybe unhook the PCM main connector and inspect, clean and put back together? Any grounds around the connector? A google search will give you the code descriptions. But i fear you will need t factory shop manual to know more. Look on ebay. That's where i get mine. If you had a terminal problem on one solenoid, perhaps it overheated the connector pins or if its shorted, its drawing too much current and upsetting others. Do all the solenoids measure the same reading? Bob With any luck, this might shed some light maybe ? This is one fault (I THINK), and to have three codes. . . . The problem is I don't have a model specific book for this, up until now I've only been told the descriptions for the codes. Of course one will be TCC or circuit, and then I suspect one of them will be tranny fluid temperature, but what about the other one ? Incidentally I did check the web resources pointed out, they were quite informative, except for one thing. How to tell if this is the problem. Hell it could be the computer, but to find that out I'd have to reset it and make it go to where it locks the TCC. Whether the solenoid is driven is one piece of info. You may have seen the burnt connector, what if the coil had shorted turns ? If so I might need a transistor in the computer. Are these things even marginally servicable or am I going to be looking at an encapsulated assembly ? (like an old tripler in a TV) It would be a real (_|_) kicker to do all this torque convertor and **** and find out all I needed was an ECG375. While I can check a wire for high or low state, I doubt there is a pressure tap for this particular mode. However, does the signal, or maybe line pressure drop when it tries to apply ? Anyone know ? Thank you all again for everything so far,and thanks in advance for whatever comes next. The main thing to me is that I don't want to burn up a new torque convertor. JURB ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#8
|
|||
|
|||
Thanks again Bob, but how did you get the meaning of those codes off Google ? I
just tried it and pretty much didn't get crap. I got all kinds of things, but nothing that defined the codes. Anyway, now I'm somewhat at a loss for specifics. How the heck would it know about other shift solenoids, as well as the TCC one ? The codes, 1-2 shift, 3-2 shift and TCC, all at the same time ? Now the question becomes how are they detecting these faults, are there mechanical state switches in the tranny or is this all coming from an error comparing the crank to the VSS, which incedentally I wonder exactly how they deal with that, being a 4WD. I guess they would need a secondary VSS on the transfer case output for the speedo, or does it just "know" ? With these codes now, remembering the symptom: Reset computer runs fine, afterwhile starts taking off in second and no passing gear. When it gets hotter it will no longer shift into first even manually. I wonder if the computer is reading the other two codes because of being in the limp home mode. Even so, how could it differentiate between anything involved at times when the TCC should be applied. When the TCC isn't applied how would it know the stall rate of the torque convertor ? Is their math that good that they can do it from the MAP or MAF along with the other engine values ? That's almost scary (lol). I say fairly assuredly that the TCC should not be applied in anything but high gear, wouldn't you agree ? There is one possible fact not known yet,,,,,,,,, is it POSSIBLE that the TCC is supposed to engage in every gear because they used a bit of a different design of convertor, like one with nice high stall, but need the TCC because it'll overheat ????? This comes up because now I remember that the thing was picked up out of town and during the trip it pushed out some fluid. It had to have been overfilled because it wasn't real low when it got home. I wasn't on the trip, but I heard there was quite a bit. Was it expansion, or maybe the torque convertor started cavitating ? A penny for your thoughts, hell I'll double it ! Thanks again JURB |
#9
|
|||
|
|||
JURB6006 wrote: Thanks again Bob, but how did you get the meaning of those codes off Google ? I just tried it and pretty much didn't get crap. Try the search phrase "DCT P0740" that should pull up this page among others: http://www.c5forum.com/ayc/1997dtc.php I got all kinds of things, but nothing that defined the codes. Anyway, now I'm somewhat at a loss for specifics. How the heck would it know about other shift solenoids, as well as the TCC one ? The codes, 1-2 shift, 3-2 shift and TCC, all at the same time ? They may not happen all at the same time. Once a code sets, it stays. Now the question becomes how are they detecting these faults, are there mechanical state switches in the tranny or is this all coming from an error comparing the crank to the VSS, which incedentally I wonder exactly how they deal with that, being a 4WD. I guess they would need a secondary VSS on the transfer case output for the speedo, or does it just "know" ? Many ways. The engine knows its RPM. It has the VSS signal. And i believe there is a signal on the tail shaft for output rotation. It just does the math. It figures on what gear it commands, figures the ratios, and goes from there. Probably looks at the internal pressures too. With these codes now, remembering the symptom: Reset computer runs fine, afterwhile starts taking off in second and no passing gear. When it gets hotter it will no longer shift into first even manually. I wonder if the computer is reading the other two codes because of being in the limp home mode. Even so, how could it differentiate between anything involved at times when the TCC should be applied. When the TCC isn't applied how would it know the stall rate of the torque convertor ? Is their math that good that they can do it from the MAP or MAF along with the other engine values ? That's almost scary (lol). Did you take the trannie electrical plug off and inspect it closely???? Did you measure the resistance of all the solenoids at the trannie plug and directly on the solenoid? I say fairly assuredly that the TCC should not be applied in anything but high gear, wouldn't you agree ? There is one possible fact not known yet,,,,,,,,, is it POSSIBLE that the TCC is supposed to engage in every gear because they used a bit of a different design of convertor, like one with nice high stall, but need the TCC because it'll overheat ????? On the older cars, this was true. On some of the newer ones i am not so sure. When TCC slip gets much above 200 rpm difference, its sets the code. (when it knows the TCC is engaged). If the TCC was grossly overheated, it will turn color. There is a thin strip of friction material that the TCC uses for TCC lockup. The TCC will work normal otherwise. www.phoenixtrans.com/html/lockuplowdown.pdf (assuming the rest of the trannie is ok) This comes up because now I remember that the thing was picked up out of town and during the trip it pushed out some fluid. It had to have been overfilled because it wasn't real low when it got home. I wasn't on the trip, but I heard there was quite a bit. Was it expansion, or maybe the torque convertor started cavitating ? Well, if you lost fluid and your level is ok, you definitely were overfilled. My relatives windstar puked when it got too hot due to VSS failure. Not a good thing for the trannie. Bob A penny for your thoughts, hell I'll double it ! Thanks again JURB ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#10
|
|||
|
|||
I looked at my shop manual and here is s a little more information: There are 5 shift solenoids in the trannie, All are fed from a common 12 volts from the fuse box, (on my truck fuse 24 10A). the input wire is "E". From "E" on the plug, 12 volts is fed to all the other solenoids. E= 12 volts to these solenoids: T= TCC clutch U= TCC modulation S= 3-2 shift B= 2-3 shift solenoid A= 1-2 shift solenoid All of these solenoids are grounded at the PCM module. They all normally have 12 volts from the fuse box, and are grounded at the PCM for solenoid operation. There are switches in the trannie to confirm to the PCM what gear its in. rev/low=N d3/d2=R d4/d2=P pressure control solenoid= D & C Bob ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#11
|
|||
|
|||
Thanks again Bob, I'll be looking into that next. Once I find those test
points, then I gotta deal with the logistics of doing this in a driveway, or on the street. Maybe I'll pick up some noid lights or something, I'll keep you "posted" JURB P.S. Just so you know I just noticed the email address showing in the posting window of my AOL newsreader appears to be picking up your correct email. The (remove) is not there. I just thought I'd let you know, because I am an extreme spam hater. Even junk snail mail, I use their prepaid SASE to send back, you guessed it, junk mail, but somebody else's. You should see what I do to telemarketers, I talk to them for a good ½ hour before finding an excuse to get off the phone right away, of course without buying anything. Funny they don't call as much. I wish I could do something like that to spammers. JURB |
#12
|
|||
|
|||
One new question;
Just exactly happens if the power is lost to all solenoids ? Fuse blows, what it just revs up and sits there, or does it take off in second or third and disable passing gear, ummm, for example. Reason I ask is that some other similar vehicles have experienced taking off in second and the dash went out. This has been found to be the ignition switch in a couple of cases. Really if the fuse blows it's blown, but a switch.In this case the vehicle doesn't have the digital dash (IIRC) and being a 4WD it might just have a seperate VSS for the speedo.Now I'm not trying to shove a symcure down your throat, but I think test one will be to see if power applies to the topside of those solenoids. Believe me, when I get back under the thing I'll check those connections, and if that proves nothing I'm going to find out what is and is not being driven. With your advice I'll definitely make sure the electrical end of it is OK before money droppage. I will do what you suggested, soon, but if you happen to know, if it were to lose all power to the solenoids, what would it do ? I think this is a crucial piece of information here. Can you drive home with the tranny fuse blown ? This also comes back to the ignition switch if it applies the voltage TO the tranny fuse. If the tranny is reporting to the PCM what gear it's in, WHY ? Because it still has valves, and maybe a pure hydraulic mode to get you home ( ? ? ? ? ) |
#13
|
|||
|
|||
I can't help on the Blazer, but I know Chrysler electronically controlled
transmissions will default to second gear if they encounter a sensor reporting a problem in what they call "limp home" mode. In most cases, with the Chrysler transmissions, this is most often caused by one of the speed sensors failing. If the speedometer still works, then it is usually the input speed sensor that has failed. If the speedometer no longer reports a speed, then it is the output sensor. Both sensors are about $25 each at the dealer and fairly simple to change (5 minute job). On the Chryslers, they tend to fail often. I've replaced two in different vehicles and each had about 50-60K miles. Another common failure in Chryslers is the solenoid pack. If the Blazer is anything like the Chrysler trans, if it fails and does go into 2nd gear, do not drive it far or long since it places a great deal more stress on the internals. Many people I know who started with a simple $25 part that needed to be replaced have ended up requiring rebuilt transmissions at up to $2500. Again, I'm not sure if this information is useful or not, but have to believe that the designs are similar and may even share third party components, such as the electronic speed sensors. Good luck! Bob "JURB6006" wrote in message ... One new question; Just exactly happens if the power is lost to all solenoids ? Fuse blows, what it just revs up and sits there, or does it take off in second or third and disable passing gear, ummm, for example. Reason I ask is that some other similar vehicles have experienced taking off in second and the dash went out. This has been found to be the ignition switch in a couple of cases. Really if the fuse blows it's blown, but a switch.In this case the vehicle doesn't have the digital dash (IIRC) and being a 4WD it might just have a seperate VSS for the speedo.Now I'm not trying to shove a symcure down your throat, but I think test one will be to see if power applies to the topside of those solenoids. Believe me, when I get back under the thing I'll check those connections, and if that proves nothing I'm going to find out what is and is not being driven. With your advice I'll definitely make sure the electrical end of it is OK before money droppage. I will do what you suggested, soon, but if you happen to know, if it were to lose all power to the solenoids, what would it do ? I think this is a crucial piece of information here. Can you drive home with the tranny fuse blown ? This also comes back to the ignition switch if it applies the voltage TO the tranny fuse. If the tranny is reporting to the PCM what gear it's in, WHY ? Because it still has valves, and maybe a pure hydraulic mode to get you home ( ? ? ? ? ) |
#14
|
|||
|
|||
"Bob Shuman" bravely wrote to "All" (17 Nov 04 08:39:23)
--- on the heady topic of " 97 Blazer 4X4 ECT problem(update)" BS From: "Bob Shuman" BS If the Blazer is anything like the Chrysler trans, if it fails and BS does go into 2nd gear, do not drive it far or long since it places a BS great deal more stress on the internals. And don't forget to replenish the engine oil as it tends to get by the rings a lot while doing over 60mph in 2nd gear. A*s*i*m*o*v .... A couple of volts below threshold. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Water Pump / Pressure Tank Problem !!!!!! | Home Repair | |||
AV problem with philips 32PW6005 | Home Repair | |||
Wiring problem | Home Repair | |||
Boiler Problem Gradually Getting Worse | UK diy | |||
CRT Contrast Problem | Electronics Repair |