Saturn Repair Questions? Ask a Mechanic for Answers ASAP
Hello and thank you for your post. I am a master certified GM tech, with 15 years Saturn experience,and can help you to resolve your issue.
this is a lot of info to digest
the thing to know about these transmissions is that all or almost all of the issues we see are either due to a bad valve body, a bad connection at the valve body, a loose input shaft nut or a bad prndl switch on the back of the trans
the codes you deem to have tell me that you may have a bad connection at the valve body (inside the valve body under the cover)
the solenoids are in teh valve body and occasionally the buss plate (black plastic connector plate) can get loose connections at the terminals where the solenoids snap in place
What's a "prndl" switch?
the transaxle range switch
(neutral safety switch)
we usually use a scan tool and make the solenoids "buzz" while wiggling the connector on top of the trans
if the buzzing starts and stops when doing that then we know the connector is bad
the loss of 1st gear combined with teh whine from teh trans tells me you probably have a loose input shaft nut
Re. transaxle switch - makes sense. What do you make of the fault codes?
the codes all point to conditions related to the solenoid connections being loose
OK on loose nut.
you may also have wiring issues leading to teh trans
not so common in 2001 but can happen
wires can be chewed by a rodent or rub on the a/c line or something
Solenoid connections is what it seems to suggest to me.
The tranmissions 'til now has acted solid except for the shift issue.
without using my $3500 scan tool to diagnose this...based solely on your symptom...I would remove the end cover and replace the input shaft nut (if it's loose) and then remove the top cover, remove the bus plate and see if the connections are loose
if they are, replace the bus plate
if they are not, replace the entire valve body
these issues affected every single S-series car regardless of year or engine type
I have a good mechanic, but I think he's concerned about spending a lot of time to diagnose and then still end up having to replace the transmission
OK on issues affecting all S-series.
but the p0789 code didn't come around until 2000 and that is almost always teh bus plate
How likely is the slam shift to damage the transmission itself?
What about the incorrect ratio thing?
as far as replacing the trans, it is rare for these trannies to fail but it can happen
the slam shifting is usually what causes that nut to loosen up
the incorrect ratio thing is caused by the shift solenoids
Going to call my mechanic and see if he has questions... Just a moment...
they can also be caused by a bad pressure regulator in teh valve body so the vb may still be bad but if you have no reverse delay or bang then I doubt the regulator is bad
it is part of teh valve body
OK. He says we need to check your suggestions before we go any farther.
What do I do now. I'll click accept and we'll come back if we have any more questions?
ok. so do that and let me know how you make out
if he has a scan tool that can buzz the actuators in the trans (solenoids) have him do that while wiggling the connector in teh top cover. not the connector that bolts to the cover, the plastic piece that pokes through the cover that the bolt on connector bolts to
OK. Thanks for now...
He has a scan tool, but don
wiggling that will cause the buss plate to shift from side to side and can cause the buzzing to start and stop indicating a bad connection
....don't know if it can make them buzz. I'll check...
if you need me again you can post your info or question here even after you click accept.
thank you and good luck.
I am here if you need me
Long hiatus for various reasons but finally getting in to the transmission. Report on status:
Word from the mechanic this morning is that resistance reading on all five solenoids is within range of 4.8 to 5.2 ohms: 2nd=5.1, line pressure=5.2, TCC=4.9, 4th=5.0, 3rd=4.8. I believe those are measurements made through the connector with buss plate still on.
He says the input shaft nut is not loose.
Next to check the prndl switch.
Currently the transmission is stuck in 4th gear; it won't shift down into 1st.
Question that comes to my mind is how do I know the proper signal is getting to the solenoid in the first place?
Other than that, it looks rather like there is an issue in the valve body.
at idle all of the solenoids get 12v and the ground is pulsed on by the trans computer
this cannot easily be tested without a scan tool or lab scope
if you have 12 v at pins J, E, A, C and G then the powers are ok
if it is stuck in 4th gear, be sure the battery voltage is above 12.6
a bad alternator can cause the stuck in 4th gear symptom if battery voltage is too low
otherwise, I would think the valve body is bad
of course any codes stored will lead us to what needs to be checked. are there any codes?
if you have a p0731, p0732, and p0733 then the vb is most likely bad
and replacing the valve body will cure both a bad connection at the buss plate as well as a faulty valve in the vb assembly so either way the valve body will fix this unless the computer is bad which is unlikely
I'd be pretty certain of a valve body on this one
Re. 2001 Saturn SL (SL1? 1.9 litre engine) electronic automatic transmission fault codes showing up along with intermittent slam shift behavior:
Mechanic has had valve body and buss plate out. Buss plate is good. Took valve body apart and one valve a bit scuffed, which he polished and replaced. Other than that no problems evident with the valve body. The valve body has been replaced relatively recently. It's a Trans-Tech valve body. That explains why the buss plate looks good. Transmission oil is very clean (mechanic was impressed). So somebody has done a lot of work on this transmission for that very problem and evidently didn't solve it.
The PRNDL switch was working when he took it apart. But perhaps it is intermittent? Will check it again.
Wiring didn't show any evidence of rodent or other damage, but need to check the wiring harness again.
Assuming PRNDL and wiring pass repeat check, now what? Could be an issue with the PCM (power control module)? How to test/verify that? Perhaps some funny interaction from the BCM? Computer has corrupt firmware? Are you aware of any firmware updates (Can it be updated)? Any service bulletins on this?
Re. the transmission codes that showed up, is it significant that there are no codes for 1st gear? You would think that there would also have been a 1st gear code. Codes that showed up were:
The mechanic is a troubleshooter. I believe he thinks the slam shift is happening as a 3rd to 2nd shift.
Thanks again. I see I must have transcribed the one code incorrectly. I believe it should read, "P0733 Incorrect gear 3 ratio" instead of P0333
Report back on 2001 Saturn S-series with 1.9 litre engine re. electronic automatic transmission fault codes showing up along with intermittent slam shift behavior:
Looks like the sticking valve he shined up was the prime issue. So the issue was indeed in the valve body. Mechanic had a scope on it to graph the solenoids during a test drive and all solenoids including TCC working positively with no fluttering. He said even a human hair would be enough to make the valve stick. It wasn't seized (as in frozen) before he took it apart and cleaned it, but it was very sluggish, he said.
Shifting is beautiful now and very smooth. Has never shifted so good since we got it.
Best part about it is that now we have our own local Saturn expert :-)
Thanks for your input.
Transmission buzz, another mis-shift:
Don't know if the mis-shift and the buzzing are related. Buzzing is faint and most evident when the heater fan is off and can be best heard with the door open and/or the hood open. The type of buzz makes one think of the solenoids but don't know why they would buzz. Buzz is there (continuous) when the shift selector is placed in neutral, and also when placed in 2nd. When shifting into Drive, 3rd, Reverse, and Park there is a brief buzz and then it becomes quiet. Is this buzzing normal? Service manual mentions the PCM pulse width modulates the solenoids for the Torque Converter Clutch (TCC) and Pressure Control (PC) solenoids, but why would I only hear that in neutral and 2nd?
Had a mis-shift "hiccup" again yesterday on the transmission with codes:P0732 Saturn Gear 2 Incorrect RatioP0733 Saturn Gear 3 Incorrect Ratio
Can't say 100% what it was like because my son was driving, but from his description it's like it shifted out of 1st into 3rd, then didn't like the combination and abruptly shifted to 1st, then shifted up again. Fault code light came on, which were the P0732 and P0733 codes. I cleared off the codes and no reoccurrence yesterday evening and this morning. Speculating if there may have been some condensation causing erratic behavior? Temperature was about -6C (21F). Might have something to do with the transmission fluid temperature sensor? Last evening took it for a 12 mile highway run out an then back again. Prior to yesterday's mis-shift I had noticed a couple of fairly abrupt down-shifts on deceleration at about the 60 km/h range (between 35 and 40 mph). Other than that the transmission shifts as smooth as silk, barely noticeable if one isn't accelerating hard.
Will convey your suggestions to the mechanic.
Mechanic said input shaft nut was not loose, but not sure how he gauged that. Could be that it needs to be re-torqued, but it seems to me I've seen somewhere that it must be replaced with a new nut.
Valve body was not replaced now, but has been replaced in the past, being a Trans-Tech valve body. Mechanic disassembled the valve body and shined up the sticking valve. Not sure which valve was the sticking valve. The valve was scored a bit, he said. But maybe needs to polish the valve with polishing compound on a buffing wheel and not just clean with fine sandpaper.
I'm speculating if the valve were still sticking a bit and not quite completely returning, that it might buzz against the solenoid if the PCM is pulse width modulating the PC valve?
1) Where can I locate an input shaft nut? So far not having success locating a supplier for the nut. Can you recommend a supply source? Can you give me a part # XXXXX the nut? Is it the nut only, or is there a kit with washers/spacers or some such?2) Can the existing nut be re-used if it is removed and cleaned up? Or do they get damaged in the process of installing/removal?3) How much play is tolerable? The mechanic said that when he had the side cover off that there was no movement at all in the gear behind the nut. Can shift faults be created if the nut is imperceptibly loose? Or are there other components behind the gear that are affected?4) Might the input and output speed sensors be suspects in this case?
My thought was to replace the nut and make sure we have that base covered. The mechanic suspects it's not the nut but still some issue in the valves.
2001 Saturn SL1 (1.9L) saga:
Thought I'd give you an update on the ongoing saga of the Saturn 2001 SL1 Transmission:
Thought we had it solved with shining up the sticking valve, but not so. Was good for a short time, then began "bumping" on the down shift, I suppose 4th to 3rd, such as when letting of the gas and coming into town off the highway, when it would downshift at about 60km/hr. Then got another slam shift on acceleration from a stop sign.
Mechanic took the valve body apart again but this time when back together and he took it for a test drive he got a slam-shift, but now there was no 4th gear. Well, at least now he experienced it firsthand himself ;-)
Decided to take it in to Trans-Tech for road test/diagnostic. Road test concluded it looked like the transmission itself not the problem. They took the valve body apart twice and still not solved, though did find some gasket issues. Evidently it's the transmission. So had the local mechanic remove the transmission and shipped it in to Trans-Tech for a rebuild. I understand they found the input feed tube was bent or constricted or some such. Of course now all the clutches are rebuilt too and whatever else they do. Should work perfect, right?
Transmission back in the car, but now 3rd gear only. Trans-Tech wants it back to check it again with their breaker box. Only this time will have to get it hauled into the city because too hard on the transmission to take off without 1st gear. Seems strange it's still giving issues because Trans-Tech would have tested it on their dynamometer.
I don't know what fault codes are showing now. Forgot to ask. Will inquire and report back.
Stopped back at the garage and inquired about the Saturn SL1 fault codes. They are the same ones that I reported back in April 2012:
PO732 Incorrect gear 2 ratio P0733 Incorrect gear 3 ratio P0766 Shift solenoid D performance or stuck off P0783 3 to 4 shift problem P0789 Shift timing solenoid intermittent
They will have tested it on the dynamometer before they shipped it out, so it seems highly unlikely that the transmission itself is the issue now, but I suppose it's not hard to leave something amiss on an item that complex. The shop foreman told me he would be rebuilding it himself.
It actually sounds like something electrical to me this time. I understand they did replace one solenoid. Have to have the car hauled in there for them to check it out 'cause it's not driveable now.
Anyhow, thought you would like to know. Will let you know when/if we do finally resolve this. I'm sure it's probably quite valuable on its own merit by now as a unique case study :-)
Car is back and working fine.
To make a long story short, this last time around with the rebuilt transmission back in and only had third gear, the problem turned out to be the connector (10 wires or so in the connector). Tech I spoke to said someone somewhere had back-probed the connector incorrectly from the rear and in doing so opened up the connectors so they didn't grip the pins correctly. He said it's easy to miss. Apparently the connector has also been updated so it doesn't have the issue of water getting in. He said we shouldn't have any more trouble with that transmission.
Other than that, the feed tube was broken when the transmission came in (I believe that's internal). The first time I took the car in for testing they had taken the valve body apart twice and found issues with gaskets, but exactly what that means is another question. So, good that they found and corrected some issues there, but evidently that wasn't the main issue.
I guess the moral of the story is do the homework and look after the basics before one starts into exotic repairs. Unfortunately not many mechanics are also electrical experts. I felt all along that it seemed like an electrical issue, but you've got to have some place to work to tackle that yourself, especially in winter - and I don't.
Thanks for your help and advice.
Another update on this Saturn SL1 (range switch saga): All still not well despite the rebuilt transmission. P0706 code showed up. Concluded it's the range switch. Installed an aftermarket switch, all seemed fine, then within a day the P0706 code back. Took it back, readjusted switch, all seemed fine and reliable after considerable testing. Next day P0706 code back! Concluded switch faulty; got a replacement, installed it, and within a day P0706 code back (seemed susceptible to cold). Got an OEM (AC Delco?) part, installed it, and so far so good. Looks like we finally have a reliably functional vehicle as of Nov. 22, 2013, nearly 2 years after the trouble started! Makes me wonder if the first range switch on the vehicle was the primary problem all along; it's gone in the trash by now so can't check if it was OEM.