Tri-City Saves Customer 2375.00 vs. Competitor Quote

Case Study:  2001 Chevrolet Tahoe, 4L60E Transmission, 73,265 miles, Transmission Shifts Hard After a Long Drive

Customer Concern: After a long drive on the highway, when I get on surface streets, the transmission shifts ruff all the way to the house, and I can tell something is wrong.  However, the next morning the truck works great again, and I may not feel a problem again for another couple of days or even weeks.

Shop A Diagnosis: This is a beginning of a transmission failure – so trade it off now or start saving for a new transmission – estimate $2800

Shop B Diagnosis: Torque converter is bad & you need a new one - estimate $1500.00

Tri-City Transmission Diagnosis: We scanned the vehicle’s computer and found a diagnostic trouble code (DTC) of P1870 definition of which is “transmission component slipping”.  Our technician went for a road test and found the torque converter clutch slipping at an rpm of approximately 25 at cruise speed and at 60 loading the converter slightly.  We would expect to see the number at 5 rpm slippage or less when the torque converter lock up clutch is applied.  When it is not applied and at a stop light this number would be approximately 800 rpm or the speed of the engine.  The slightness of this slippage is not perceivable by the driver, but rather through the read out on the scanner’s data stream.  The torque converter clutch apply valve in valve body needs repair.

Tri-City Recommendation and Final Resolution: Remove valve body from transmission (repair does not require major transmission removal); re-bore and sleeve torque converter clutch apply valve cylinder; install new TCC apply valve; re-install valve body, and service transmission with new fluid & filter.  Estimate $425.00 with a 1-day turnaround time in most cases.

Customer Comments on This Repair: After two places told me bad news, I reluctantly came to Tri-City Transmission at the insistence of a co-worker that overheard that I was having a transmission issue.  I was not confident in the abilities of either of the first two shops and left very confused.  I know nothing about cars and therefore have to rely on my gut to know if I am being treated fairly and working with people who know there stuff.  You guys have great communication skills, and with the way you explained things to me in laymen terms, I knew you have expertise and a passion for what you do.  With your company’s charisma and strong reputation, you could have convinced me to buy a transmission.  Instead, you had my best interest in mind and only sold me a minor repair.  Your actions clearly reflect your business philosophy of integrity and honesty.  In today’s world, those values seem to be rare.  In the future, should I or any of my friends ever be in need of a transmission repair, I also will, as my coworker did, insist they come to Tri-City Transmission.  Thanks again, Tammy.

Tri-City Transmission of Tempe Comments: This is a very common repair at Tri-City Transmission.  The customer’s usual description is after a long drive, I have a hard shift.  However, the problem is gone in the morning.  This is the reason there typically is a P1870 diagnostic trouble code (DTC) stored in the computer, the definition of which, is transmission component slipping.  Most shops see this as a good excuse to overhaul or replace the transmission.  This is because they are not transmission specialists and they are not familiar with this type of problem.  Generally no one sees the check engine light on because it’s very intermittent and the light may not have illuminated for long.  It will only set after long drives on the freeway.  When the code is active, the computer compensates for the slip of the torque converter clutch (TCC) & boosts the EPC (electronic pressure control) to max and you will generally notice a hard 1-2 shift (where inertia is greatest).  After a key cycle the problem will go away until another long drive where the condition is right for the P1870 to set again.  If the problem has not gone untreated for too long, it can be repaired in the valve body (minor repair) where the torque converter clutch apply valve is worn out.  If it has gone too long you would also look at replacing the torque converter itself (slip ratio in data stream makes that determination).  A lot of transmissions get replaced unnecessarily for this particular code.

One other way people find out about this problem is when they fail emission because the testing facility tells them they have a code for the transmission and it’s P1870.  They are surprised because they have never experienced any issues with the transmission because it is very intermittent and often goes un-notice.  Now, they can’t pass emission until it is resolved.

There are specific technical service bulletins from General Motor (GM) referring to this problem.  Other vehicles that it affects with the same transmission are:  Chevrolet ½ ton pickup, Chevrolet ½ ton Suburban, Chevrolet ½ ton Tahoe, Oldsmobile Bravado, Chevrolet Express Van, Chevrolet Trailblazer, Chevrolet S10 Blazer, Chevrolet Impala, Chevrolet Camaro RS or SS, Chevrolet Avalanche, Chevrolet Corvette, Chevrolet Caprice, GMC Envoy, GMC Safari, GMC Sonoma, GMC Yukon, GMC Safari.  This Transmission is called many things; 4L60, 4L60E, 4L60-E, 4L65, 4L65E, 4L65-E, TH700R4, TH700-R4 or even TH700.