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PostPosted: Wed May 04, 2011 7:27 pm 
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Joined: Fri Apr 01, 2011 3:50 am
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Year and Trim: 1998 Pontiac Bonneville SE
Bonneville has bee running great but today all the sudden it starts shifting " HARD " Not really Slipping . and would pulse at low speed under light acceleration and 3-4 would act weird and up and down shift under light acceleration. Then it had a hard shift into 2nd and the " Check Engine Light Came On " First time ever . The Parts Store was only a feww hundered feet ahead , So i stoped in and Scaned this code PO742 . Details "Torque Converter Clutch Circuit Stuck On " I cleared the code and went to drive it home and it is acting Normal again .

So, What is it ? :dontknow:


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PostPosted: Wed May 04, 2011 7:38 pm 
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Location: Lincoln, NE
Year and Trim: 1998 SE (w/ SLE package)
I have this EXACT issue sometimes, with the same code. I ripped this directly from a site regarding this issue:

Quote:
Trouble Code P0742 TCC Stuck ON:

When this trouble code is set the pcm will command max TCC and lock adaptive shifting. This code can be broken down into three potential problem areas as found to be common in the field.

1. This problem can be a mechanical problem. Possible causes of this could be a bad or stuck TCC switch that signals the pcm of current TCC operation. Another cause though not common is a stuck TCC switch or apply valve. If it is physically stuck in the wrong position it can cause the TCC to be stuck on all the time and even kill the engine when the vehicle is put into gear.

2. This problem can be found to be an electrical problem. If the wire from the TCC pressure switch to the pcm is grounded anywhere in the path it can throw this code. This could be a wire shorted inside the trans on the internal wiring harness or the actual engine wiring harness. If the wire is grounded the pcm thinks that TCC is on when it shouldnt be and will throw the code.

3. This problem can be a hydraulic problem. This is the most common cause of this code that I have found and stems back to a clogged TCC solenoid, not because it failed. Excessive debris in the transmission or a failing torque converter lockup clutch can cause the solenoid to have debris stuck inside and this causes a restriction in fluid flow through the solenoid. If the solenoid can not bleed off the pressure the TCC can be stuck on. If the wrong TCC solenoid is installed during an overhaul this problem can also arise as a late 4L60E solenoid is identical but does not operate the same and acts like a clogged solenoid. As mentioned in problem #1 a stuck TCC apply valve is a physical problem but causes a hydraulic problem because the fluid pressure will not properly bleed off because the valve is stuck in the wrong position instead of being able to move freely in the bore of the valve body.

Above are the common causes of this code, there are other possibilities but those are what generally causes the fault. A thorough diagnosis is the only way to determine what is really at fault and a new TCC solenoid should never be assumed as the actual problem until verified.

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1992 Chevrolet Lumina base:TOTALED (died at 110k)
1989 Buick Reatta:SOLD (sold at 105k)
1991 Pontiac Bonneville LE:SOLD (sold at 225k)
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1998 Pontiac Bonneville SE:CURRENT (bought w/ 145k)


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PostPosted: Wed May 04, 2011 7:52 pm 
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Year and Trim: 1998 Pontiac Bonneville SE
I just did a pan drop less than 100 miles ago , and the fuild was dirty but now its decent . this is the first time it has done this

Also just installed a 180 Stat ? and a/c was on and car temp was only 180ish at max , maybe the trany needs to be warmer hence the 195 stat ?


Last edited by LouderBonneville on Wed May 04, 2011 7:54 pm, edited 2 times in total.

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PostPosted: Wed May 04, 2011 7:57 pm 
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Location: Lincoln, NE
Year and Trim: 1998 SE (w/ SLE package)
Not sure, I had a pan drop done not long ago and my t-stat is a 195. I think I still had issues before the pan drop but I don't recall.

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1992 Chevrolet Lumina base:TOTALED (died at 110k)
1989 Buick Reatta:SOLD (sold at 105k)
1991 Pontiac Bonneville LE:SOLD (sold at 225k)
2001 Cadillac Seville SLS:SOLD (sold at 140k)
1998 Pontiac Bonneville SE:CURRENT (bought w/ 145k)


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PostPosted: Wed May 04, 2011 9:01 pm 
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Location: Hillsboro, Oregon
Year and Trim: 2000 SSEi
2004 GMC 2500HD
2013 Buick Regal GS
Thermostat temp does nothing for the transmission. All it does is regulate the coolant flow through the motor.

Check the connectors to the transmission and if you have the wiring diagrams, you should be able to check the coil of the solenoid. Other than that, I would keep an eye on it and see if it starts happening regularly or the error code never goes away.

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