93ss406

iTrader: (6)

Hey guys I've got a problem. Just bought a 98 trans am auto. I test drove the car for about 30 min with no issues. I bought car and was on my home and had been driving about 45 min. The tach dont work I stopped at red light and went to leave and would not come out of 2nd gear. I tried it manual and when I put it in 3rd it was goin to neutral. When I put it in drive it was like it went to neutral and would have go half throttle and it would jump back to 2nd. If I leave it in 2nd when the rpms get up it acts like it'll shift but seems like it goes to neutral. It has a po748 solenoid code and po654 tach dont work. Any advice would be highly appreciated

Ed Wright

iTrader: (1)

Sounds like the 3-4 clutch pack.

93ss406

iTrader: (6)

Would it just go out a once like that

Ed Wright

iTrader: (1)

Could be the solenoid. Somebody needs to diagnose it for you. Not likley you can do it in the driveway.

93ss406

iTrader: (6)

I'm goin to pull pan sat if there ain't no debri or nothin I'm goin to try solenoid. Is there one just for 3rd and 4th don't know a lot about it

Ed Wright

iTrader: (1)

Before you pull the pan, you might consider getting a shop manual, and working the diagnostic tree for that code. May be electrical instead of internal. Cars get that old, wires get brittle from heat & vibration, and break. Doing proper diagnostics could save you a lot of time, money and mess.

joecar

Start by checking the ATF level and condition/color...

then work thru this diagnostic chart (what Ed said): http://www.ls2.com/boggs/a4/DTC%20P0748%205.7.htm

also is filter ok and not clogged/cracked...?

There is a good chance the problem is mechanical, but you should first eliminate anything else (like the P0748 you're seeing).

93ss406

iTrader: (6)

I changed the 2-3 solenoid and put new filter and fluid in it. Now it's takes drive hard and 1-2 is even acting weird but still no 3 or 4

Joe W

I was getting the same code and shifting problem. My vehicle is a project that is almost road worthy so it rarely gets out of the garage. I replaced the alternator today and the code disappeared. I haven't taken it out yet but thought I'd pass it on FYI....

99SS#20

iTrader: (13)

I would look into the tach issue. I am not positive on this application, but many go into a "Limp Mode" when certain engine parameters are lost, tach being one of these. This will cause the trans to suddenly get "stuck" in second, with no obvious issues. I am skeptical of an internal trouble due to the suddenness and the symptoms. I will check some manuals if I get the chance for you.

93ss406

iTrader: (6)

I thought that might have something to do with it at 1st.after I put the solenoid in it now it goes from park to reverse and drive very hard and 1 to 2 shift has got rough. I put another cluster in it and tach still don't work.the fluid was burnt smelling also when I pulled pan

99SS#20

iTrader: (13)

Was there any aluminum or steel particles in the fluid? Burnt smelling fluid is not good, but the age of the fluid and the amount of driving that was done while not shifting could be a factor.

With the tach not working on multiple instrument clusters I would look for a connector or sensor issue in the engine bay. The TCU does use the engine RPM as part of its shifting schedule.

On a brighter side, the parts are easy to get and inexpensive for these transmissions. There are a couple of special tools you will need to either make or buy.

moehorsepower

iTrader: (3)

Unfortunately yes, seldom does it give you any warning on the 3-4 pack. I had been driving my car with no problems one day, then got on the hi-way and after the 1-2 shift, nothing, It was like in neutral, I had to limp home in 2nd gear, 3-4 clutch pack went south.Burnt smelling trans fluid, that already tells the story..

93ss406

iTrader: (6)

No particles in pan. I have a six speed coming so aint worried bout it lol