Locking torque converter question?

GPster · June 03, 2011, 01:33:49 PM

I have an '04 Jeep Grande Cherokee Loredo special with the full-time AWD transfer case on the back of the 4L six with automatic transmission. Now with all that information here's the question for trying to narrow down a problem. We thought it was a problem with the cruise control but then realized it happens on regular driving above 50 MPH even without the cruise control. If you watch the tachometer the RPM will change about 200 or 300 RPM. The RPM just raises/lowers (hunts?). At first we thought it was jumping between gears but the transmission isn't appearing to shift. Would this be a torque converter trying to decide it it wants to lock or not? The dealer that we bought this thing from new (about 93,000 miles ago) has had the franchise go to another dealer that is creating an AUTO WORLD so I'm afraid to have this thing checked by any dealer and I don't want to go to a regular repair place (good) without some hint of a cause. We're afraid to ignore this and just wait until it becomes an expensive repair. GPster

rooster · June 03, 2011, 07:57:56 PM

Quote from: "GPster"I have an '04 Jeep Grande Cherokee Loredo special with the full-time AWD transfer case on the back of the 4L six with automatic transmission. Now with all that information here's the question for trying to narrow down a problem. We thought it was a problem with the cruise control but then realized it happens on regular driving above 50 MPH even without the cruise control. If you watch the tachometer the RPM will change about 200 or 300 RPM. The RPM just raises/lowers (hunts?). At first we thought it was jumping between gears but the transmission isn't appearing to shift. Would this be a torque converter trying to decide it it wants to lock or not? The dealer that we bought this thing from new (about 93,000 miles ago) has had the franchise go to another dealer that is creating an AUTO WORLD so I'm afraid to have this thing checked by any dealer and I don't want to go to a regular repair place (good) without some hint of a cause. We're afraid to ignore this and just wait until it becomes an expensive repair. GPster

Maybe you can hook up a scan tool and watch the RPM,s that way! Wayne would know about this!

jaybee · June 03, 2011, 11:29:38 PM

Interesting this would come up. Not sure what kind of Jeep it is but #2 son's girlfriend and her Mom were trying to bring a Jeep with just over 90,000mi to IA from Sandusky, OH. They noticed what they described as "felt like the transmission was trying to drop out of gear" at highway speeds. They left it at a dealer in Elkhart or South Bend, rented a car to bring the girl the rest of the way in, then picked up the Jeep on the way back.

Dealer said they couldn't find anything wrong with it.

enjenjo · June 03, 2011, 11:51:47 PM

I have seen several things things that can cause this. Worn TPS. It will check ok at both ends of the travel, but will have a bad spot in the middle of the travel. Bad wiring to the VSS can cause it. O2 sensor can cause it. And a defective PROM can cause it. No clue to which it is in your case.

wayne petty · June 04, 2011, 01:10:23 AM

everybody is right..

first... lets check the TSBs... i highlighted a few that i would really think you would want to examine.. and there seem to be a bunch of recalls.. that you might want to call jeep with your vin number and date of production on the door label.. see if they had been done..

second... how is the fluid color... have you had it serviced lately.

the transmission filter kit for it only seems to be 11 bucks.. the 5 or 6 quarts of ATF+4 are more than that.. be sure to read the sediment in the pan... when the filters clog or melt.. they restrict the fluid and this can effect the high speed operation.. and low speed operation also...

http://alldatadiy.com/TSB/04/040418d2.html

Automotive Recall and Technical Service Bulletin Titles for 2004 Jeep Truck Grand Cherokee 4WD L6-4.0L VIN S.

TSB Number & Issue Date TSB Title
J14 NOV 09 Recall - Potential Seat Heater Fire

F17 JUL 06 Recall - Front Seat Heater Element Replacement
D13 MAR 04 Recall - Crankshaft Position Sensor Replacement

D05 MAR 04 Recall - Tire/Rim/Inflation Pressure Label Replacement
C12 MAR 03 Recall - Steering Gear Assembly

TSB Number & Issue Date TSB Title
D14 APR 04 Recall - ECM Programming for OBD Malfunctions

TSB Number & Issue Date TSB Title
C07 FEB 03 Campaign - Avoiding Unintentional Vehicle Movement

TSB Number & Issue Date TSB Title
24-002-10 JAN 10 A/C - HVAC Sub-Assembly Part Availability
21-021-08 SEP 08 A/T - Repair/Replacement Guidelines
21-014-07 OCT 07 A/T - ATF + 4 Fluid Usage
08-030-06A AUG 06 Engine Control - PCM Initialization Procedure
24-006-06 AUG 06 A/C - Musty Odors When Hot/Humid
05-003-06 JUL 06 Brakes - Front Brake Inspection RE Lawsuit BER-L-4883-04
21-010-06 APR 06 A/T - ATF+4 Fluid Usage/Applications
23-014-06 MAR 06 Wipers/Washers - Wipers Smear or Streak Winshield
22-001-05 DEC 05 Wheels - Caring for Chrome Wheels
18-037-05 OCT 05 Engine Controls - Flash Programming Failure Recovery
21-015-05 SEP 05 A/T - 45RFE/545RFE Delayed Engagement After Filter R&R
18-029-05 JUN 05 Engine Controls - Co-Pilot Support & Correct Cable Usage
08-024-05 MAY 05 Electrical - Radio Equipment Installation Recommendation
19-005-04A OCT 04 Steering - Steering Column Pop/Tick/Creak Noise
02-006-04 AUG 04 Steering - Lead or Drift To Either Side of Road
08-027-04 JUL 04 Safety Systems - Inadvertent Damage/Disabling
18-028-04 JUN 04 A/T - Torque Converter Lock-Up Inoperative
02-002-04A MAY 04 Suspension - Front Suspension Squeak/Squawk Noises
23-012-04 APR 04 Interior - Wooden Trim Panels Scratched
08-014-04 MAR 04 Audio System - Intermittent Loss of Audio
23-009-04 MAR 04 Interior - Popping/Clicking Noise in Front Seat Frame
18-008-04 FEB 04 Engine Controls - Idle Drone/Transfer Case Lamp ON
08-002-04 JAN 04 Body Controls - Horn Chirp Upon Vehicle Entry
18-040-03 NOV 03 Engine Controls - Erroneous DTC P0135 (O2 Sensor) Set
23-026-03 OCT 03 Body - Poor Air Deflector to Hood Fit
08-030-03 OCT 03 Electrical - No Auxiliary Power to Trailer Tow Harness
08-028-03 SEP 03 Audio System - 'CD ERR' Message Displayed
25-002-03 SEP 03 Emissions - Long Crank Time to Start Engine
18-032-03 SEP 03 Engine Controls - MIL ON/Erroneous O2 Sensor DTC's
18-031-03 SEP 03 Fuel System - Hot Start Misfire/MIL ON/DTC's/Rough Idle
03-002-03 AUG 03 Drivetrain - Rear Axle Vent Cap Leakage
19-005-03 AUG 03 Steering - Power Steering Fluid Usage
09-003-03 AUG 03 Engine - Multiple Cylinder Misfire
06-002-03 AUG 03 M/T - Excessive Clutch Slippage
08-016-03 JUN 03 Restraint Systems - Optimized Air Bag Control Module
23-015-03 JUN 03 Body - Wind Noise from Top Rear of Front Doors
23-013-03 MAY 03 Body - Roof Rack Air Turbulence/Wind Whistle
24-003-03 MAY 03 A/C - System Sealer Usage Prohibition
25-001-03 FEB 03 Emissions - Ticking Sound With Engine Idling
22-001-03 FEB 03 Tire Pressure Monitor - Temperature Change Effects
07-005-02 DEC 02 Cooling System - Intermittent MIL ON/DTC P1499 Set

wayne petty · June 04, 2011, 01:30:25 AM

i would try cycling the key on.. off.. on.. off..on off and on.. within 10 seconds.. 3 times on in 10 seconds and i understand the check engine codes will be flashed or displayed... i have heard this works.. not tried it first hand.. i just plug in my handy 98614...

i also have an older OTC monitor extended.. but its has only 98 cartridges.. since i only work on older cars usually.. it does much of what i need..

next.... i would try to find somebody with a scan tool....

a generic scan tool like the HF 98614 will display the codes and live data...

read starting at section 5.2

http://manuals.harborfreight.com/manuals/98000-98999/98614.pdf

jeep and chrysler changed a lot of how its all done in the early 2000 models.. they went to CAN on a lot of systems..

decent scan tools can also record a section of data stream so you can go back to the shop and compare whats happening to whats normal.

the 98614 scan tool is about 120 +tax...

the next better scan tool up thats easily available that will be really useful is the OTC 3499N.. but is just under 500.oo...

see if you can get somebody with a obd 2 scan tool or code reader to grab your codes... the transmission codes will be in the P0700 to P0799 range.. but please post all the codes you get.. if any...

looking at the TPS voltage on a scan tool but does that model have drive by wire yet.. still checking...

i don't have a service manual on anything that late.. yet...

i will check more tomorrow.. spend all day tracing down why a accord speedo would only read 20 mph.. and pulse a little when the wheels turned... after repairing several stretched and broken wiring harnesses and the sensor pigtails... the transmission R and R guys must have forgotten do disconnect them... turned out i needed to tear the cluster out and apart.. its got 3 layers of circuit boards... i resoldered a bunch of terminals including the chip on the back of the speedo its self.. put it all back together and it worked.. not only shifted properly.. but the speedo and odometer worked again..

GPster · June 04, 2011, 07:43:31 AM

Time to trade? The list scares the hell out of me. Advance Auto and I assertained a problem with the Throttle Position Sensor a while back and I changed it. Had another problem where the sixth cylinder was mis-firirng and a replacement (warrantee on a new plug) plug didn't cure it. The trusted (this is why) explored the Internet and found a problem with a wire that would separate with stretching around the straight six motors. He repaired it and charged fairly. I wondered about reading the codes but with this problem only existing at highway speed I figured it would only tell when the problem was occuring. Maybe I'll need to have the tranny checked. It's only been done once. Never would have kept it this long. Would have traded it if Jeep hadn't dropped the adjustable passenger seat

wayne petty · June 04, 2011, 11:21:23 AM

what... that list scares.. you.... thats the shortest list of TSBs i have ever seen.. if the list of a few recalls and tsbs is what you are talking about..

there are all kinds of things that can cause the computer to unlock and relock the torque converter clutch... including misfires... if it sets a P0300 to P0306.. it will cause TCC havoc

plug in scan tool..... a code reader... its the only way to really know what's going on..

wayne petty · June 04, 2011, 01:49:35 PM

the ignition coils do fail ...

http://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/C1263/image/4/

you might want to remove it carefully and inspect it for signs of high voltage leakage...

az only gets just over a 100 for one.. comes with a 2 year warrantee.

multi coil packs do fail... as do conventional coils... be sure to use a tiny amount of dielectric tune up grease around the inside of the boots to seal both ends ... not on the metal terminals..

if one is creative.. you might be able to remove the coil pack.. stick six spark plugs into the boots... wrap a copper wire around the shells of the plugs so the pairs are hooked all together.. or just in pairs..

open the gaps up .. and have somebody crank the engine.. see if you get a decent spark across paired plugs.. you have to test all the plugs at the same time... a nice hot blue spark... not a whimpy orange one..

this is a major cause of misfiring and P0300 misfire codes..

i have cleaned coil leaks with brake cleaner.. covered the area with clear silicone... it has helped in the short term... but if the internal windings are shorted.. which they most of the time are.. it will not cure the problem..

GPster · July 18, 2011, 08:27:26 PM

Read the owner's manual and it was recomended that the fluid and filter be cahnged at 90,000 miles. The local trans shop had a two week waiting period and the local Jeep dealer did it the next day. I figured the fluid and the filter would be the first diagnosis so I took it and had it done there. There were no shavings in the pan and the old fluid didn't appear burnt. I took it on a trip (to a swap meet and pick up the grand daughter) and each spell of driving it appeared better. On the final leg of the trip it seemed like the RPM change from lock to un-lock was only about 500 ( or maybe my mind was pre-occupied, at a gas stop some one in front of me with a long float boat on a trailer backed up to leave and the stern of it scratched/dented the hood of my car before he took off). Who knows? GPster