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  #1  
Old 05-23-2017, 08:26 AM
AugustDiesel AugustDiesel is offline
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Default TPS Bypass Switch

I've done a lot of reading up on bypassing the TPS sensor, but haven't really found anything concrete on exactly how to do it. I'd like to install a bypass toggle switch so that I can have more control on when the TC locks and unlocks. I've seen where some install jumper wires and I think where Dmax installed a push/pull switch. I'd like to find out the following:

1) where the tps is located? On the side of the injection pump?
2) where exactly will the bypass wires plug in at?
3) what gauge wiring is best?

Thanks in advance!
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1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.
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Old 05-23-2017, 09:54 AM
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DmaxMaverick DmaxMaverick is offline
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If you want manual control of the TCC, the TPS is the LAST piece you'll mess with, if you mess with it at all. All the pressure switches inside the tranny, the brake switch and the ECM/ALDL lead need bypassed before the TPS ever comes into play. I've done this on my rigs, and a bunch of others. The TPS bypass was never needed, once the rest was done correctly. I suggest leaving it alone unless and until you have a very specific need to mess with it. If you still feel the need, try it without messing with it, first. You can always "bypass" it with 1% throttle pressure.
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Old 05-23-2017, 11:26 AM
AugustDiesel AugustDiesel is offline
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Quote:
Originally Posted by DmaxMaverick View Post
If you want manual control of the TCC, the TPS is the LAST piece you'll mess with, if you mess with it at all. All the pressure switches inside the tranny, the brake switch and the ECM/ALDL lead need bypassed before the TPS ever comes into play. I've done this on my rigs, and a bunch of others. The TPS bypass was never needed, once the rest was done correctly. I suggest leaving it alone unless and until you have a very specific need to mess with it. If you still feel the need, try it without messing with it, first. You can always "bypass" it with 1% throttle pressure.

Thanks I will give that a try. I only asked about bypassing the tps bc there are a few posts on here that recommend bypassing the tps when the tc isn't locking/unlocking when it should. But I must have misunderstood what was being suggested. I'll give the throttle pressure suggestion a try! Thanks!
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1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.
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Old 05-23-2017, 12:41 PM
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DmaxMaverick DmaxMaverick is offline
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Bypassing the TPS may be helpful for diagnosing a problem, but little else. It's a switch, not a sensor/sender. It only closes when your foot is on the skinny pedal, which allows for lockup if all other conditions are met.
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Old 05-23-2017, 12:49 PM
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It also has another purpose, in addition to TCC. It will also disengage the EGR, if so equipped.
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Old 05-23-2017, 01:14 PM
AugustDiesel AugustDiesel is offline
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Quote:
Originally Posted by DmaxMaverick View Post
Bypassing the TPS may be helpful for diagnosing a problem, but little else. It's a switch, not a sensor/sender. It only closes when your foot is on the skinny pedal, which allows for lockup if all other conditions are met.
My apologies, I meant to say the switch, not the sensor.
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1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.
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Old 05-23-2017, 04:19 PM
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DmaxMaverick DmaxMaverick is offline
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No worries. It can be a little confusing. Your 6.2L and early 6.5L (mechanical injection) both have a TPS. But, they are not the same. The 6.2L with an auto tranny (700R4) has a Throttle Position Switch. The MFI 6.5L with an auto (4L60E, 4L80E) has a Throttle Position Sensor. They are not interchangeable. Add to that, the 6.2L with a TH400 has no switch/sensor, but a vacuum valve in the same place. Clear as mud!
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Old 05-23-2017, 07:31 PM
convert2diesel convert2diesel is online now
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You may also find that by replacing said TPS, your lock-up situation may be corrected. Additionally, if you run a wire from the far right (IIRC) terminal of the OBD data port through a switch on the dash to ground, you can lock up your convertor at any time after going into 2nd gear. Just remember to turn it off when you move away from stop. After the tranny hits 2nd, your convertor stays locked. Makes for some interesting shifts.

Bill
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Old 05-23-2017, 08:10 PM
AugustDiesel AugustDiesel is offline
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Quote:
Originally Posted by DmaxMaverick View Post
No worries. It can be a little confusing. Your 6.2L and early 6.5L (mechanical injection) both have a TPS. But, they are not the same. The 6.2L with an auto tranny (700R4) has a Throttle Position Switch. The MFI 6.5L with an auto (4L60E, 4L80E) has a Throttle Position Sensor. They are not interchangeable. Add to that, the 6.2L with a TH400 has no switch/sensor, but a vacuum valve in the same place. Clear as mud!
So, to add to the confusion, what I have is an NA 6.5 (506) mated to a 700r4. The 6.5, as far as I can tell, has all the 6.2 accessories since the 6.5 was a warranty block. So, I'm assuming I have the throttle position Switch since the truck originally had a 6.2.

From what I understand, once the tc locks, it's suppose to stay locked until I apply the brakes (correct me if I'm wrong). Well, I gave the truck a good road test today and that thing was all over the place. Constantly locking and unlocking in both Drive and Overdrive.

I'll look into a new tps, but I'd still like to consider a way to manually control the tc if possible.
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1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.
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  #10  
Old 05-24-2017, 06:37 AM
convert2diesel convert2diesel is online now
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Quote:
Originally Posted by AugustDiesel View Post
So, to add to the confusion, what I have is an NA 6.5 (506) mated to a 700r4. The 6.5, as far as I can tell, has all the 6.2 accessories since the 6.5 was a warranty block. So, I'm assuming I have the throttle position Switch since the truck originally had a 6.2.

From what I understand, once the tc locks, it's suppose to stay locked until I apply the brakes (correct me if I'm wrong). Well, I gave the truck a good road test today and that thing was all over the place. Constantly locking and unlocking in both Drive and Overdrive.

I'll look into a new tps, but I'd still like to consider a way to manually control the tc if possible.
I have to assume you are using the old (88) computer. The tps had only two functions when mated to the 700R4. Controlled the EGR (if installed) and commanded the lock up. Your shift patterns are controlled with a throttle valve in the tranny connected via a cable to the throttle quadrant.

The lockup is activated any time you go into 2nd gear or higher and the throttle position is less than 1/3 to 1/2 throttle position (33% to 50%). If you want to go to full manual control of the lockup, you're going to have to disconnect the tps altogether and or the computer and install a switch in the transmission ground position of your data port (I think it is the terminal on the far right of the OBD connector under the dash). The switch will override any command from the computer.

As I said in my previous post you are going to have to be vigilant as you don't want to have the tranny going through the gears with the convertor locked up. Your brake switch will still unlock the convertor as before. Ran the Buick with this setup for close to 100K without issue, after I got used to unlocking it when appropriate. You're also going to need a piece of electrical tape to stick over the check engine light

I would try a new TPS first. You may find your issues disappear. Try the cheap fix first.

Hope this helps.

Bill
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06 Vortec Max Silverado CC SB (finally got all the bugs worked out)
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