[moentte999]

Dear Tranny People.

My 1997 blazer only 70.000 mls won´t shift in fourth anymore.

How is the process to start with the root cause analyse?

I apresciate your help and thanks in advance.


Monette999

[monette999]

Dear Tranny People,
I am Electric girl and need some help of mechanics to do a propper root cause analyse.
My 97 Chevy Blazer 4.3L won't shift in 4th gear anymore.
The engine light come on due to the no shift. No failure codes stored which give me a hint.

I could get a GM Service tool Tech2 to make a componment check, but it won't tell me any mechanical solenoid stuck trouble.

I like to check on the valve body connector if a signal is available.[U]
any quik analying procdure available before if start going to the GM Service procedure which is not comfortable to read.

Which solenoid is reponsible for the 3-4 shift? [B]
I added the connector schematic as pdf. Which are the lines to measure.
Does the 4L60E M30 has an single soleoid for 4th gear or is this a combination of several valves.

Thanks for any help,
monette999

[Henry Highrise]

Welcome to Hotrodders.....This is the Introduction forum, so it would be best if you posted your tranny question over in the Transmission forum.

[poncho62]

moving it..........

[Crosley]

With the CEL on... what codes were set?

Does reverse gear still function?

there are 2 shift solenoids. IF you have a good solid first gear(both solenoids "on") I doubt the problem is a solenoid.

Have the vehicle scanned with a quality scanner. You need to see the data stream of the ECM to the trans. Check for command for shift to 4th gear.

Has this trans been serviced recently or ever in 70k miles of the vehicles life?

[monette999]

Hello Crosley,
There was no error code listed. The engine check light is present. I forgot that failure code.

yes the reverse gear still works fine and all other gears as well except the 4th. and I have a good first gear.

What is a quality scanner? Is it like the Tech 2 from GM for onboard diagnostics.

The transmission oil was checked by shop. They said it is ok. But i doubt that a service was made before by the previous owner.

Do you mean an actuator element test with the service tool.

Is there only a ECM engine controle module or as well a TCM.

If I have a wire break or bad connection or mechanical failure and the command shift to fourth gear won't tell me anything. How can I check for this failure.Can I get a feedback signal of the shift command at the transmission connector.


Regards monette999

[Crosley]

If the check engine light is on... there is a code set. You forgot the code? Bummer, try to scan the system again or clear the codes , then drive the vehicle for several miles.

Most of the cheap "code readers" can not scan deep enough into the vehicle system to read needed info.

There are several quality scanners. I use Snap on Modis.

With all the tech stuff you are quoting & searching for , you must be reading all this stuff off the internet or something.

As I posted a quality scanner hooked into the data stream to check for inputs to the trans and back. Some wire problems do show up on a scanner hooked into the system. Some scanners read out the voltage , resistance of the solenoids & PCS systems

Also , as I posted the shift solenoids are both applied in first gear and appear to function. I doubt this is an electronics problem in your trans , possibly a mechanical failure as I list below.

You may have a worn out 2-4 band. A check of the servo cover travel with a pry bar would indicate that to a knowledgeable trans person. The servo is a multi-stage unit... 2nd gear can function fine , yet 4th gear will not hold power since a different section of the servo applies the band in 4th gear.

there could be a broken , cracked accumulator piston for 4th gear... a worn, scored up bore of the 3-4 accumulator.

good luck , post back with info when you can.

[monette999]

This is the GM tool called Tech2.

I will scan it the next days again.

[transbuilderguy]

I am going with leaking servo seal or as crosley said a cracked accumulator piston

[monette999]

Hello

Where to look for the servo seals?
and could it be any accumulator piston or the 3-4?

Are they located in the valve body?


thanks

[monette999]

Here the failure code0753

1-2 Shift Solenoid Cuircut Electical

This is the failure code.
What does it mean? I have a 1,2,3 gear, can shift them all. As well a reverse.

Hope you can give some good advice

Monette99

[monette999]

Hello Hotrodders,
I have a P0753 failure code stored in my ECU and thy symton in no
fouth gear.

The failure code descition is: 1-2 Shift Solenoid Circuit Electrical.

I am confused a bad solenoid and oly loosing the forth gear.

Thanks for help.


Monette999

[Crosley]

Swap in a pair of new shift solenoids (2) , see if that fixes the trans.

I'd add a new filter and pan gasket too.

[monette999]

Dear All ,
thanks to the good advices. I replaced the 1-2shift solenoid and now it works perfect.

monette999

[monette999]

Dear Tranny Poeple,
recently my 97 Blazer is not going in reverse.
I feel some resistance but the grear in not going in. It put it back on park
and then repeat.

Than it is working.
How do you swith on reverse on the solenoids?

I apresciate any help.

Thanks Monette999