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Discussion Starter · #1 ·
Howdy Planet!

I've been doing a lot of interstate travel lately, and I'm noticing a recurring trend with my trans shifting into overdrive. Most times, if the trans is warm, it'll shift into overdrive and stay there until I give it enough gas to downshift. Other times it'll run in 3rd gear and stay there until it decides to randomly shift into overdrive. When I say randomly I mean there's no tellin when it'll shift into overdrive.

Years ago a buddy of mine wired a switch in his Cherokee (yes I know Jeeps aint Isuzu's) to override the trans and lockup the torque converter. I'm wondering if there is any way I could wire a switch to have the same effect on my 4L30E; keeping it locked in overdrive whenever I engage this switch.

If anybody has any thoughts, or experience with this feel free to chime in, and let me know what I should do.

Thanks yall!

-Robert
 

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Pin A on the 5 pin overdrive case connector is the TCC solenoid control. The color code on a 99 is Red/Yellow, a 98 is probably the same. Applying +12 VDC to this line will cause the TCC to engage.
 

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If you do that, you want to power it through the cruise control switch that is on the BRAKE pedal lever.

Not the brake switch. The brake switch only has power when you are braking. The cruise control switch is the opposite. It only has power UNTIL you step on the brakes.

You don't want the TCC to stay locked up when you are braking.

I hope that it is already set up inside the case, so that the TCC will only lock up when the trans shifts into OD...

The above is the way I set mine up. (On a 93 jimmy.) I powered it through the CC switch at the brake lever. And inside the case, the power still doesn't get to the TCC until it switches into OD. (At 40 mph.)

So mine shifts into OD, and locks the TCC.

Any time I am below 40 mph, the TCC is not locked up. Any time it IS locked up, (above 40), and I hit the brakes, it unlocks because the power to it, is cut.
 

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Discussion Starter · #4 ·
Buster do you have a picture of the TCC solenoid control, and/or a wiring diagram for it?

Jeff, do you have a picture of the CC switch on the brake pedal lever?

I understand what both of yall are describing well enough to be able to do this, but when I finally do I want to make sure I do it right the first time.

Thanks yall!

-Robert
 

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TKEPA251 said:
Buster do you have a picture of the TCC solenoid control, and/or a wiring diagram for it?

Jeff, do you have a picture of the CC switch on the brake pedal lever?

I understand what both of yall are describing well enough to be able to do this, but when I finally do I want to make sure I do it right the first time.

Thanks yall!

-Robert
Like I said, mine's on a gmc jimmy. I don't know if a pic will do you any good.
 

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Kable said:
Not sure how much different the 30 is over the 60 but
http://www.summitracing.com/parts/BMM-70380/
I think they use the same fluid and that's about where they cease to have any similarity. The 4L30E was built in France, the 4L60E was built in Michigan. You know how the French are. :|
 

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Discussion Starter · #10 ·
Jeff, it'll give me a rough idea of what I'll be looking at, every little bit helps.

CatFuzz said:
I think they use the same fluid and that's about where they cease to have any similarity. The 4L30E was built in France, the 4L60E was built in Michigan. You know how the French are. :|
They like to surrender.

-Robert
 

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I suggest before you wire up a manually operated TCC you attach a 12 VDC LED indicator lamp between the TCC solenoid control line (Pin A) and chassis ground. That way you can monitor the TCC lockup command signal to determine if the signal is being sent by the PCM and not acted upon or not received at all. If the signal is being sent and not acted upon due to a defective solenoid or a TCC hydraulic system defect, installing a switch will be a waste of time.
 

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Buster28 said:
I suggest before you wire up a manually operated TCC you attach a 12 VDC LED indicator lamp between the TCC solenoid control line (Pin A) and chassis ground. That way you can monitor the TCC lockup command signal to determine if the signal is being sent by the PCM and not acted upon or not received at all. If the signal is being sent and not acted upon due to a defective solenoid or a TCC hydraulic system defect, installing a switch will be a waste of time.
Good idea.

Robert: I'll get that pic, later today.
 

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Discussion Starter · #13 ·
Buster28 said:
I suggest before you wire up a manually operated TCC you attach a 12 VDC LED indicator lamp between the TCC solenoid control line (Pin A) and chassis ground. That way you can monitor the TCC lockup command signal to determine if the signal is being sent by the PCM and not acted upon or not received at all. If the signal is being sent and not acted upon due to a defective solenoid or a TCC hydraulic system defect, installing a switch will be a waste of time.
I agree that this is a good idea, but I've got around 10k on this new trans. I'm seriously hoping that the TCC solenoid isn't defective already, but I suppose it aint outta the realm of reason.

I'll try the LED light first, then go from there. Thanks for the suggestions!

-Robert
 

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TKEPA251 said:
Jeff, it'll give me a rough idea of what I'll be looking at, every little bit helps.

-Robert
I crawled in there with the camera.

Took 27 pictures with the camera stuffed in there as many different ways as I could figure... And still didn't get one single shot of the switch.

As I was doing this, I remembered.......

When I did this, I gave up looking for the switch under there. Instead I went straight to the cruise control.

Since it gets it's power via the aforementioned brake pedal switch, I just went to the power line that went TO the cruise control, and tapped in there.

I was concerned that it might affect the cruise control, but it hasn't.
 

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Discussion Starter · #15 ·
Selador said:
I crawled in there with the camera.

Took 27 pictures with the camera stuffed in there as many different ways as I could figure... And still didn't get one single shot of the switch.

As I was doing this, I remembered.......

When I did this, I gave up looking for the switch under there. Instead I went straight to the cruise control.

Since it gets it's power via the aforementioned brake pedal switch, I just went to the power line that went TO the cruise control, and tapped in there.

I was concerned that it might affect the cruise control, but it hasn't.
So more or less I should wire the TCC switch to the brake pedal switch associated with my cruise control?

-Robert
 

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TKEPA251 said:
So more or less I should wire the TCC switch to the brake pedal switch associated with my cruise control?

-Robert
Check out your wiring diagram.

You should be able to figure out whether there even is a switch of the sort or not. Then, following the diagram, you can see if the cruise control is fed power from that switch.

If you find both of the above to be true, then yes. Splice right into that wire.
 

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Discussion Starter · #17 ·
Selador said:
Check out your wiring diagram.

You should be able to figure out whether there even is a switch of the sort or not. Then, following the diagram, you can see if the cruise control is fed power from that switch.

If you find both of the above to be true, then yes. Splice right into that wire.
I'll do some more research before I go cuttin and splicin. Thanks for your help Jeff.

-Robert
 

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I just read your initial post again and I am confused. Are you trying to install a switch to manually control TCC lockup or a switch to manually control 4th gear(overdrive)?
 

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Discussion Starter · #19 ·
Buster28 said:
I just read your initial post again and I am confused. Are you trying to install a switch to manually control TCC lockup or a switch to manually control 4th gear(overdrive)?
Is that not the same thing? I've always been under the impression that torque converter lockup occurs in overdrive. I guess I'd like to install a switch to keep the trans in overdrive.

-Robert
 

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1st, 2nd, 3rd and 4th(overdrive) gear selection is controlled by 2 transmission shift solenoids referred to as Shift A and Shift B. The PCM energizes and de-energizes these solenoids to select the correct gear. For example, in 3rd gear A is energized and B is de-energized. To shift into 4th gear A is de-energized, so both A and B are de-energized in 4th. The shift points are determined by vehicle speed, throttle position, power mode switch position and other load conditions.

The TCC is controlled by the TCC solenoid which is also under control of the PCM, the TCC can be commanded to be locked up in 2nd, 3rd or 4th gear depending on engine coolant temperature and ATF fluid temperature and other engine/vehicle conditions.

Controlling the shift solenoids manually with switches could be done but a better solution is to identify and repair the 3-4 upshift problem.
 
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