Transmission problem - won't shift out of first

[Seang58]

Hi folks. I hope someone can help. I have a 2002 GC Laredo, 4.0 engine, 42RE transmission. Here is the problem: error code shows only P0135 for the O2 sensor. It shifts into reverse fine, shifts into drive fine, but while driving it won't shift out of first. I have had it up to over 3000 rpm. There is a whine coming from the transmission which changes pitch when shifted from park into reverse, and from reverse into drive. After changing the radiator, water pump and thermostat, still the same problems. Any suggestions or ideas are greatly appreciated.

 

[JPNinPA]

Have you checked or flushed the transmission fluid lately?
What color is the fluid?
Are you sure you are in drive?
When you put it in park or reverse the indicator and shifter position line up properly?

 

[Seang58]

I got it from my son. He said it was flushed but some time ago and he does not know if they put ATF 4 in or not.

 

[TerryMason]

I'd say it's worthwhile to drain it and fill it with new fluid, as well as a new transmission filter. If you do it your self It shouldn't cost more than $25.

 

[greg92jeepxj]

I agree as a first step is to flush the trans fluid and change the filter . Check the throttle valve cable for proper adjustment . Check,the fuse box for any fuses and relays associated with the trans since it uses a TCM ( transmission control unit ) too. It's an overdrive electronically shifted trans so that's something to look at. But the first thing is the trans fluid to see if there's anything that dosen't belong there like burned fluid of metal shavings and clutch plate material . Not thinking the worst but always good to check . Starting to think it's a TCM issue but the DTC ( diagnostic trouble code ) should have come up .See if anyone you may know can put a scan tool on it to check TCM activity . Usually that's done on a dynometer but can't hurt to check it curb side.

 

[Seang58]

I agree as a first step is to flush the trans fluid and change the filter . Check the throttle valve cable for proper adjustment . Check,the fuse box for any fuses and relays associated with the trans since it uses a TCM ( transmission control unit ) too. It's an overdrive electronically shifted trans so that's something to look at. But the first thing is the trans fluid to see if there's anything that dosen't belong there like burned fluid of metal shavings and clutch plate material . Not thinking the worst but always good to check . Starting to think it's a TCM issue but the DTC ( diagnostic trouble code ) should have come up .See if anyone you may know can put a scan tool on it to check TCM activity . Usually that's done on a dynometer but can't hurt to check it curb side.

I have read that on the 2002 GC the TCM is in the PCM, it isn't separate. Does that make a difference in diagnostics?

 

[Seang58]

I suppose changing the fluid and filter is a good step. If it turns out to be a governor solenoid it won't hurt to do it again.

 

[Seang58]

Have you checked or flushed the transmission fluid lately?
What color is the fluid?
Are you sure you are in drive?
When you put it in park or reverse the indicator and shifter position line up properly?

Good points. I'll check to see if they match up. As for a flush I'm concerned that with a problem existing it could cause more of a problem than is already there.

 

[greg92jeepxj]

I have read that on the 2002 GC the TCM is in the PCM, it isn't separate. Does that make a difference in diagnostics?

I'm a bit rough on later models and didn't know the TCM is integral with the PCM . That would make it easy to diagnose with a scan tool , I would say since a TCM must be diagnosed manually and only the drivetrain functions such as solenoids are seen through a scan tool if the scan tool is updated and equipped to read such data . That's when we got to give in to a good diagnostics shop , unfortunately . But dtc's , if logged and found are a good thing to provide direction .