This morning when I left for work I felt the trans shift from 1st to 2nd but would not shift into 3rd. No check engine light. On my way home from work I stopped about 6 times at a stop light or stop sign.
After two of these stops it did shift into 3rd without any problems. Not sure if I went fast enough to shift into 4th. If I put the shift lever into 1st it drives fine. If I put into 2nd it drives fine. If i put it into 3rd it still only goes to 2nd and won't shift into 3rd. Reverse is fine. All sounds normal and it shifts just fine from 1st to 2nd. When in Drive it won't come out of 2nd. I drove it to 3,000 RPM and backed off. The couple times it did shift into 3rd on my way home it felt normal. No slipping.

Being there is no Check Engine Light, could this mean it's not a electrical problem and could be a mechanical problem like 3/4 clutch pack or a bad sprag?
Any other problem that could cause this?

Thanks
Jim

 

When I see titles like yours, I instantly think of a bad 3/4 clutch pack which is what happened to me. But the symptoms of a bad 3/4 clutch pack is that the shift from 1 to 2 is fine but when it shifts to 3, it will act as if it has shifted into neutral and the engine will rev. This revving is the slipping clutch pack.

I wonder if there are codes set that do not necessarily trigger the check engine light to go on. You might go to an auto parts store and see if their scanners note any set codes. I learned that of my local shops, the code reader used by the O'Rielly's store was able to read more than the one used by the Autozone. I mention this only as advice that you might have to go to more than one place to find a place with code reader that more capable than others. It just so happens the one used by the O'Reilly people was more capable.

 

I have a cheap Code Reader from Harbor Freight. Cen-Tech 98614. This code Reader show no codes or pending codes. Is it possible that there is a Code and if my Code Reader won't read the code, so my reader shows no Codes?

I did a test drive yesterday. If I stay around 1600 RPM for 20 to 30 seconds with my foot just barley on the gas it will shift into 3rd and accelerate fine. I did this 3 times and all 3 times it shifted into 3rd. If I drive normal and get above 2000 RPM it will not shift into 3rd. I really would like to try figure this out. My Blazer is a 2004 with 120,000 miles. I did $800 on it last year for control arms. I did $1200 two months ago for the spider injectors. I am not going to spend any more major money. It's just not worth it so it would be nice if this would be a fairly cheap fix.

Thanks
Jim

 

Regarding the code readers, they do not all have the same capabilities. I don't know about the Harbor Freight one but it might be worth taking to an autoparts store to see if their scanner can see codes your cannot.

As a for instance; I have a super simple OBDII code reader too but I had to the truck to the autoparts store for them to confirm where the fault was with the airbag sensors.

Have you done any transmission service or maintenance recently? Have you checked the fluid level?

 

My transmission went out about 4 to 5 years ago and I had a rebuilt one put in for $1800. I've put about 25,000 miles on it. Fluid level is fine. Color looks good and no smell. I've never done any service since the rebuilt has been installed.


Jim

 

Jim
You stated in first post there is no slippage, it just stays in second, If 3/4 clutch pack was going out or gone there would be slippage as if it was in neutral. So one would think it's not as bad as it could be.
Check all wiring too the transmission, including the speed sensor, as Christine recommended take it to get the codes read,
A fluid / filter change won't hurt, just change out the amount of fluid that was lost by dropping the pan, not a full flush.
Pay attention to the internal wiring and look for problems,
I would change out the shift solenoids while I had the pan off, my best guess at the moment is you have a loose wire connection or a bad 3/4 shift solenoid.

 

I have family here from out of state so I will take it to the store to have the codes read one day this week. When I took my Blazer in to the shop last they told me I have an oil leak up high and getting oil on everything. The weird thing is I never see oil on the drivway. I wonder if the oil got into a connector on the transmission. How many electrical connecters are there on the outside and where are they? I will check those and if oily I can clean to see if that helps.

Thanksa for all the help

Jim