Our Community is 940,000 Strong. Join Us.


Trans flipp'n out


gmbwrenchn
12-26-2008, 05:20 PM
97'''' Blazer 4x4 LT. 147K MILES. Auto transmission. Just recently the trans is acting funny. When I take off from a stop, the rpm''''s go real high then it shift''''s hard into 2nd........ and won''''t shift any more. I do have the "engine service light on" which I know I have to pull the code, but I just wanted to get some possible ideas now. I have had the code PO740 CODE come up in the past , but it seem to go away. Thanks for the help and I''''ll be sure to post back with the code soon.
Got the codes today. PO440 & PO306. No codes on the trans. showed up. This thing is flip''''n out!! When it shifts, it almost takes my head off it shifts so hard. Got to start out in #2 gear position from a stop, then shift into "D" so it won''''t rev so high. I really don''''t want to take it in to get stroked. Anything I can check myself? Thanks.
Here''''s some more info on this............looks like I need to manually shift from a stop, starting in 2, then 3 then "D". Even around corners I need to down shift to 2, then 3 then "D" I thought it may be a fluid problem but fluid is fine. I''''m lost. Also.....the speedometer is fluctuating......it won''''t move until I get up to about 30 mph, then it moves up from zero to the speed.

MT-2500
12-27-2008, 09:04 AM
Also.....the speedometer is fluctuating......it won''''t move until I get up to about 30 mph, then it moves up from zero to the speed.

That needs to be fixed first.
The trans needs speed signal to shift right.
It needs repaired before driving it.If it is slaming into gear it is going to rip it out that way.

But 97 has a lot of ign switch problems.
Check out that switch real close.

Get it on a good transmission/engine/transfer case capable scanner and check out the lose of speed sensor signal.

Have you checked the speed sensor wiring at transfer case?

gmbwrenchn
12-27-2008, 09:43 AM
"But 97 has a lot of ign switch problems." As in on the column? How do I check that?

"Get it on a good transmission/engine/transfer case capable scanner and check out the lose of speed sensor signal." Do you have a place or model # in mind where I can get this kind of scanner? E-bay? Thanks for the help.

MT-2500
12-27-2008, 11:04 AM
A good volt meter will test electrical part of ing switch.
Check for proper power in and out of it.
HAS IT EVER BEEN RPLACED?

As to the scanner a snap on or a GM tech 11 are one of the best.

But are high dollar.
Can run up to 3-5 grand.
Sometime e Bay has them .

FOR A ONE TIME TEST FIND A GOOD REPAIR SHOP AND HAVE THEM TEST IT OUT FOR YOU.

Good luck

gmbwrenchn
12-27-2008, 12:33 PM
Switch has never been replaced. Heard a lot about those switches that year. Is it just the switch that goes bad or is it the switch with the whole harness too. Is it a project to replace? Any forum links on replacing it would be appreciated. The air bag SCARES ME!! And also.......that speed sensor switch. Would you just replace the thing? It's Gota be bad, wouldn't ya think? Can always return it. Thanks.

MT-2500
12-27-2008, 02:28 PM
Speed sensor needs tested out on a good scanner.

Go to the s-10 how to and there should be a how to on ign switches.
But again it needs proper testing before throwing parts at it.
Good luck

gmbwrenchn
12-27-2008, 03:47 PM
Ok.......here's the latest. Just took her on the freeway for about 20min. When I got off, it's shifting FINE NOW!! And the speed-o WORKS FINE TOO!! Maybe a trans. sludge problem? Maybe a good flush and fill? Changed it last at 23k miles ago {3 yrs to the date} Never gave it a flush. Are there flushing agents for this on the market? Thanks.

MT-2500
12-27-2008, 04:24 PM
You need to get it on a good scanner and see what happened.
No on the flush unless you want to kill it for sure.


To Flush or not To Flush ?
Just like Kenney Rodgers said you have got to know when to fold and when to hold.
If the fluid has high mileage 100K or over or is real dirty you had better hold.
On a trans that has had good regular service at 50K or sooner a flush is good.
But be ware of jiffie/quick/wallmart /fast lubes that offer power and fast flushes.
They have abused and over rated the trans flush.
They have a habit of using one fit all fluid out of the same barrel that fits all.
They just throw in a bottle of additive to make it fit all. Or worse they pitch in a bottle of cleaner or dope in it that can do more harm than good. And will tell you the filter does not need changing with a flush.
Just remember that all new fluid makes a high detergent cleaner that will break loose all varnish and dirt and grit in the trans and drop it in valve body and solenoids.
Always change the filter and go easy on or use no dope and cleaner.
Adjust/check the bands and linkage on the trans that have bands and adjustments.
Always use the trans fluid the trans/manf calls for. And be aware that some manf have changed the type of fluid specs since the trans was manf.
Some fords have changed the specs and a lot of cry/dodge have gone to the newer type of fluid on their trans service.
Also some fords have tsb’s and require a total complete trans flush to cure trans shifting problems. Some as low as 30K
If a person does not have a flush machine a old 5 gallon bucket and a couple of rubber hoses to connect to the cooler lines and with the other end in the bucket will make a good flush machine. Just put the hoses in the bucket and start the engine and start pouring fluid into the trans until the fluid running into the bucket gets good and clean.
It usually takes 16-20 qts. To get a good flush.
Flush or No flush always service the trans filter and trans on a good regular basic.
People that keep the serviced have a lot less trans problems.

gmbwrenchn
12-27-2008, 04:50 PM
Will a good scannner tell what happened even if it's running fine now? Does it keep a log of errors?

MT-2500
12-27-2008, 05:29 PM
They have a memory like a elephant.
Also may have stroed histoty and freeze frames.
But when it is acting up you can read out sensor data and tell more about it.
Good Luck

gmbwrenchn
12-27-2008, 06:32 PM
So scrap the flush but a change of the fluid is ok? I can still take it in with no current problems and get some info from a scanner read? I'm not gona drop 2 or 3 grand on a scanner so I'll take it in to a good auto shop..........what should I ask them to do? Have it scaned with a scanner with a print out? Thanks again.

MT-2500
12-28-2008, 10:27 AM
So scrap the flush but a change of the fluid is ok? I can still take it in with no current problems and get some info from a scanner read? I'm not gona drop 2 or 3 grand on a scanner so I'll take it in to a good auto shop..........what should I ask them to do? Have it scaned with a scanner with a print out? Thanks again.

Just tell them what it is doing and they should know what and how to check it.

Lot of places do not do scanner print outs.
The scanner reading by someone that knows how to read it out is what is the main thing.
Good luck

gmbwrenchn
12-28-2008, 11:35 AM
Thanks much for the help.

MT-2500
12-28-2008, 11:54 AM
You are welcome and let us know how it goes.

gmbwrenchn
01-01-2009, 07:23 PM
I do want to run something by you that I was thinking about which MAY have something to do with this acting up. About a week before I had this problem, I had disconnected the ABS in both front wheels. {I hate ABS in winter} first time I have done this. The car ran fine with it disconnected, for about a week, then that''s when these problems started. I decided to reconnect the ABS system, thinking that I was going to have to take it in to get it looked at, so I didn''t want the ABS light on. Well that day, I reconnected it, the car,while on the freeway, later that day, seem to go back to normal operation. Did this have something to do with screwing up the PCM????? Thanks.

Add your comment to this topic!