No overdrive.

[DeltaBravo]

Hello all,

If you have a moment, I have a couple of question in regards to my 2004r. I've got a 87' GN with little knowledge of the trans. Car runs great with no other known issues.

A couple of weeks ago, I was driving home and I noticed my RPM's were higher than normal. So I checked my gear selector and moved it back and forth from D to OD...Car stayed in 3rd and wouldn't up shift. At this point I'm doing about 60mph.

Since then, I've double and triple checked the TB cable (pulled all the way to firewall, mash on peddle to reset) Reset to previous setting, no change noticed. I've checked the fluid, smells good an bright pink. I did add some fluid because she was slightly low but that didn't change the overdrive issue.

My questions are...

is it safe to drive?
is there anything else I can check (without pulling the trans)?


Thanks,
Damon

Oh...and I'm not trans smart, so speak slow

 

[TexasT]

miles? has it been overhauled?
has it made many wot 3-4 shifts?

 

[DeltaBravo]

miles? has it been overhauled?
has it made many wot 3-4 shifts?

Any time I have made wot, it's been in D, not overdrive. I can't speak for the previous history. Unknown miles on the tranny. It has been rebuilt...allegedly . I don't know exactly when, or with what parts and by whom.

Is it safe to drive without harming anything? Is there anything else I can check...externally? Are there any test that can be performed to determine further action?

Thanks

 

[INEEDAGN]

if you can find access to a scan tool, you can log the 3-4 shift. see if the 4th gear pressure switch ever closes and if you can log a ratio change when that happens. Could be that it's hitting 4th but not locking up.

 

[DeltaBravo]

if you can find access to a scan tool, you can log the 3-4 shift. see if the 4th gear pressure switch ever closes and if you can log a ratio change when that happens. Could be that it's hitting 4th but not locking up.

Scan tool? no....I don't have access to one. But would any scan tool work? I'm assuming I would need a OBDI to OBDII adapter.
Any recommendation on a type of scan tool?

Again, speak slowly! I'm not very versed in tranny language. Your saying the pressure may be good for the fourth gear circuit, but the switch (something electrical) isn't working? And if this 'switch' doesn't work, the transmission will not shift into fourth.

When you say "you can log the 3-4 shift", how would I log this with a scan tool if it's not shifting into 4th?

Thanks again

 

[INEEDAGN]

No. The trans shifting 1-4 is completely hydraulic and will do its thing regardless of outside electrical input. the only thing electrical is the lockup solenoid for the torque converter. HOWEVER. there ARE 2 pressure switches on the valve body for 3rd and 4th gear, which close with hydraulic pressure and send a signal to the ecm when the trans hits 3rd and 4th. so if you have a scan tool on it, you can see if the 4th gear pressure switch gets flagged as closed when it tries to shift into 4th. if it does, and you don't see an rpm drop when it does, you can pretty much assume the trans is coming out. cause if the valve body/governor is working enough to close the switch, there wont be anything "easy" to fix to make 4th engage from there. It is possible that the torque converter clutch is not engaging, which will also make rpms higher than they should at cruise.

you need an obd 1 scantool

 

[DeltaBravo]

No. The trans shifting 1-4 is completely hydraulic and will do its thing regardless of outside electrical input. the only thing electrical is the lockup solenoid for the torque converter. HOWEVER. there ARE 2 pressure switches on the valve body for 3rd and 4th gear, which close with hydraulic pressure and send a signal to the ecm when the trans hits 3rd and 4th. so if you have a scan tool on it, you can see if the 4th gear pressure switch gets flagged as closed when it tries to shift into 4th. if it does, and you don't see an rpm drop when it does, you can pretty much assume the trans is coming out. cause if the valve body/governor is working enough to close the switch, there wont be anything "easy" to fix to make 4th engage from there. It is possible that the torque converter clutch is not engaging, which will also make rpms higher than they should at cruise.

you need an obd 1 scantool

Thank INEEDAGN,

I'm following, i think. If there is the 'right pressure' to activate the switch but not shift into 4th, then the problem is internal (4th gear related).

Torque converter theory...don't think it's that but what do I know. Car shift fine from 1-3...but no forth, RPM's just keep climbing the faster I go. Just like normal WOT in D.

RPM's around 2900 at 55-60mph.

As far as a scan tool, I will look into that.

 

[INEEDAGN]

if you don't have free access to a scan tool you can probe one of the wires on the trans connector and see if it grounds when its supposed to go in 4th. buti have to look to know which pin it is.

 

[DeltaBravo]

if you don't have free access to a scan tool you can probe one of the wires on the trans connector and see if it grounds when its supposed to go in 4th. buti have to look to know which pin it is.

I remember reading about that...don't remember where! I will do some more searching.

Same concept with a multimeter if I remember correctly.

 

[standupjskiguy]

Perhaps you could check the shift linkage to see if it is off a little?
Like maybe it looks to be in OD when it's still too much in drive?
If I'm reading the above posts correctly, the switches don't control the
shift into OD, they just report it to the ECM so they wouldn't be the cause
of no OD.

 

[regan j]

So you had OD and now you dont? Did it shift into 4th and lockup? Now it doesnt? Quick check, while driving at highway speed, put your left foot under the brake pedal and pull up. It that makes changes into lockup, the brake switch is out of adjustment. This is assuming your trans is shifting into 4th. As stated above somewhere, make sure your trans is manually shifting into 4th.

 

[DeltaBravo]

So you had OD and now you dont? Did it shift into 4th and lockup? Now it doesnt? Quick check, while driving at highway speed, put your left foot under the brake pedal and pull up. It that makes changes into lockup, the brake switch is out of adjustment. This is assuming your trans is shifting into 4th. As stated above somewhere, make sure your trans is manually shifting into 4th.

It's not a 'lock up' issue. My converter is functioning as advertised. It's a overdrive (or 4th gear) issue. Will not shift up into 4th gear.

I made a call to Dave Husek...what a stand up guy. Doesn't know me, but he talk to me as if we have meet before. Very helpful, explaining what to look for and some test that can be done. He even told me to call him back when I have the valve body exposed so he can walk me through (while on the phone) where to apply air pressure to simulate hydraulic pressure...

Because I live in Alaska, he looked into shipping cost of sending my unit to him vs just buying one of his cores. As it turns out, it is more cost effective to buy one of his.

In one phrase...When the time is right, I won't look any further for anyone else. He has my business, stand-up dude!

Thanks everyone for the assistance. For now, I have a couple of things to look at. It may be something simple with the value body, but if it isn't than it's deeper in the tranny.