1994 Chevy Suburban shuddering

Tiny
MRBILL57
  • MEMBER
  • 1994 CHEVROLET SUBURBAN
  • V8
  • 2WD
  • AUTOMATIC
  • 190,000 MILES
Hi there,
I have this 'burbie - actually my wife's, and it is our tow vehicle for a 25' travel trailer.

For a couple years it has been shuddering at highway speeds. Started out in a narrow speed range, which has widened. Give more throttle or less and it stops. Most prominent in OD. Not much in Drive.

Have been told it is the Torque Converter. Have read that it might be the TCC solenoid. The TCC is supposed to be disengaged by the brake switch and when I press the pedal if it is doing the shudder, it DOES NOT STOP shuddering (foot still on gas to keep up speed). So either the brake switch is not canceling it or the TCC is not the problem?

The tail bearing has just a little side-play at the front of the driveshaft, and the rear end was replaced last year.

I have thought about replacing the TCC solenoid and mabe the TC. But the not cenceling thing makes me think it is not that.

Am going to check the TPS - hear that can cause it. I swear it seems like a mechanical thing not an ignition or fuel-system thing, because of the speed range and the sensitivity to throttle.

It is very annoying and I know it is not good on the drive train.

We are going to Florida on a 350 mile trip next week, towing our 25' trailer. It will be in drive for that. Last Spring we made the same trip, and it was not too bad. I planned to fix her before this trip, but just got the funds to do that this week. Arrgh!

I want to make a proper diagnosis.

If it is the TC, then what brand do you suggest? O. Has a Pro-King for $200 but I have not looked at other suppliers, brands or prices.

I think it is a 4L80E, but not sure yet.

I might change the TCC solenoid and filter, and refill with new fluid, but have heard that that can make one quit, and as we are going on a trip I might want to wait till we return. Of course, I don
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have the same problem?
Yes
No
Tuesday, September 29th, 2009 AT 11:45 PM

3 Replies

Tiny
MERLIN2021
  • EXPERT
Automatic Transmission/Transaxle Torque Converter Replacement TECHNICAL SERVICE BULLETIN Reference Number(s): 01-07-30-010C, Date of Issue: May 12, 2008 Affected Model(s): 2009 and Prior GM Passenger Cars and Trucks; 2009 and Prior HUMMER H2, H3; 2009 and Prior Saturn Cars and Light Duty Trucks (Except VTi Equipped Vehicles (RPO M16 and M75); 2009 and Prior Saab 9-7X; with ALL Automatic Transmissions and Transaxles Supercedes: This bulletin is being revised to add the 2007-2009 model years. Please discard Corporate Bulletin Number 01-07-30-010B (Section 07 - Transmission/Transaxle). Related Ref Number(s): 01-07-30-010, 01-07-30-010A, 01-07-30-010B, 01-07-30-010C ARTICLE BEGINNING SERVICE INFORMATION The purpose of this bulletin is to help technicians determine when a torque converter should be replaced. Below is a list of general guidelines to follow. The converter should NOT be replaced if the following apply: DTC P0742 - TCC stuck on is set. This code is almost always the result of a controls condition (i.E. Stuck TCC solenoid/valve). Experience has shown that this code rarely indicates a mechanical concern within the torque converter. " The fluid has an odor or is discolored but no evidence of metal contamination. " Fine metal particles (traces of metal flakes/gray color to fluid ) are found in the converter. This is not harmful to the torque converter. " The vehicle has been exposed to high mileage. " A small amount of wear appears on the hub where the oil pump drive gear mates to the converter (RWD only). A certain amount of such wear is normal for both the hub and oil pump gear. Neither the converter nor the front pump assembly should be replaced. " The torque converter should be replaced under any of the following conditions: The vehicle has TCC shudder and/or no TCC apply. First complete all electrical and hydraulic diagnosis and check for proper engine operation. The converter clutch may be damaged. Also, the converter bushing and/or internal O-ring may be damaged. " Evidence of damage to the oil pump assembly, pump shaft, turbine shaft, drive sprocket support and bearing, or metal chips/debris in the converter. " Metal chips/debris are found in the converter or when flushing the cooler and the cooler lines. " External leaks in the hub weld area, lug weld or closure weld. " Converter pilot is broken, damaged, or fits poorly into the crankshaft. " The converter hub is scored or damaged. " The transmission oil is contaminated with engine coolant, engine oil or water. " If excessive end play is found after measuring the converter for proper end play (refer to Service Manual). " Page 1 of 2 Automatic Transmission/Transaxle Torque Converter Replacement -1994 Chevrolet Subu. If metal chips/debris are found in the fluid filter, or on the magnet, and no internal parts in the unit are worn or damaged. This indicates that the material came from the converter. " The converter has an unbalanced condition that results in a vibration that cannot be corrected by following Converter Vibration Procedures. " Blue converter or dark circular ring between lugs. This condition will also require a complete cleaning of the cooler and a check for adequate flow through the cooler. " Converter bearing noise determined by noise from the bell housing area in Drive or Reverse at idle. The noise is gone in Neutral and Park. " If silicon from the viscous clutch is found in the lower pan (4T80-E ONLY). "

TESTING.

TCC TESTING Converter Clutch Solenoid Disconnect harness connector to Torque Converter Clutch (TCC) solenoid. Measure resistance between TCC solenoid terminals. Solenoid resistance should be greater than 20 ohms. See Fig. 114. Converter Lock-Up Signal At Transmission 1. Warm engine to operating temperature. Raise vehicle and support suspension where necessary to prevent damage to drive axles. 2. Disconnect converter clutch connector at transmission. Connect a test light across converter clutch harness terminals. Start engine and place transmission in Drive. Accelerate vehicle to 45 MPH and note test light. 3. If test light is not on, check solenoid power supply wire of harness for open or short to ground. Check ground circuit for open between harness connector and PCM. If harness is okay, see CONVERTER LOCK-UP SIGNAL FROM PCM. Converter Lock-Up Signal From PCM 1. Warm engine to operating temperature. Raise vehicle and support suspension where necessary to prevent damage to drive axles. 2. Connect a test light to battery voltage. Touch TCC control driver terminal with test light. See Fig. 114. Accelerate vehicle to 45 MPH and note test light. If test light does not illuminate, problem is a faulty PCM connector or PCM. NOTE: When diagnosing converter clutch problems, ensure engine and vacuum systems are operating properly. For torque converter clutch electrical circuit information, see WIRING DIAGRAMS. NOTE: Some solenoids have an internal pressure switch in series with the solenoid winding and will not show continuity until that pressure switch is applied by transmission hydraulic pressure.
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Wednesday, September 30th, 2009 AT 1:29 PM
Tiny
MRBILL57
  • MEMBER
Thanks. No, it does not.

Like I said, the shuddering does not seem to be that the TCC is on/off/on. Because when shuddering, stepping on the brake with throttle applied does not do anything to change it - still shudders.

Do you think it is a tranny issue, prop shaft bushing in the tailpiece, or maybe something else like the TPS?

How much side-to-side is typical on the tail connection at the driveshaft?

Is a valve maybe not switching properly? Would you recemmend filter and new fluid?
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Wednesday, September 30th, 2009 AT 1:39 PM
Tiny
MERLIN2021
  • EXPERT
TCC TESTING Converter Clutch Solenoid Disconnect harness connector to Torque Converter Clutch (TCC) solenoid. Measure resistance between TCC solenoid terminals. Solenoid resistance should be greater than 20 ohms. See Fig. 114 . Converter Lock-Up Signal At Transmission 1. Warm engine to operating temperature. Raise vehicle and support suspension where necessary to prevent damage to drive axles. 2. Disconnect converter clutch connector at transmission. Connect a test light across converter clutch harness terminals. Start engine and place transmission in Drive. Accelerate vehicle to 45 MPH and note test light. 3. If test light is not on, check solenoid power supply wire of harness for open or short to ground. Check ground circuit for open between harness connector and PCM. If harness is okay, see CONVERTER LOCK-UP SIGNAL FROM PCM. Converter Lock-Up Signal From PCM 1. Warm engine to operating temperature. Raise vehicle and support suspension where necessary to prevent damage to drive axles. 2. Connect a test light to battery voltage. Touch TCC control driver terminal with test light. See Fig. 114 . Accelerate vehicle to 45 MPH and note test light. If test light does not illuminate, problem is a faulty PCM connector or PCM. NOTE: When diagnosing converter clutch problems, ensure engine and vacuum systems are operating properly. For torque converter clutch electrical circuit information, see WIRING DIAGRAMS. NOTE: Some solenoids have an internal pressure switch in series with the solenoid winding and will not show continuity until that pressure switch is applied by transmission hydraulic pressure.


http://www.2carpros.com/forum/automotive_pictures/62217_TCCsub_1.jpg



Any codes? Service engine light on? Check tailshaft mount! Get under it and push up on the mount, if tail goes up, mount is No good.
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Wednesday, September 30th, 2009 AT 1:51 PM

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