What to do when a GM 6T40 BAS Hybrid loses line pressure
After overhaul, a GM vehicle equipped with the 6T40 BAS Hybrid transmission has a complaint of little or no movement.
Diagnosing diagnostic codes
The codes being diagnosed in this article are: P0507: Idle speed performance higher than expected P0871: OD pressure switch rationality P0934: Line pressure sensor circuit low A 2006 Jeep Commander using a 545RFE transmission arrived at our shop from an independent muffler and general repair facility with three codes: P0507, P0871 and P0934. The codes
Keep an eye out for 6L80/90 defective oil pumps
The complaint After replacing the pump assembly in a 6L80/90 transmission with a new GM pump the vehicle returns with symptoms that would appear to be caused by a low fluid condition: it falls out of gear at a stop and has low line pressure. Upon further inspection the sump filter, which was also a
Avoiding 4L60-E harsh shifts and engagements
The complaint The complaints are harsh engagements and shifts. The scan tool data reveals that there is no amperage command to the EPC solenoid therefor the line pressure is at maximum. There are no transmission codes stored, there are lean codes stored in the ECM. The ABS or the VSC (vehicle stability control) lights may
Fixing 4L60-E 1-2 shift issues
The complaint A 1993 Chevrolet 1500 with the 5.0-liter engine and 4L60E transmission has a complaint of second gear starts. The truck seemed to start off in first gear on an initial cold start but would stay in second gear at a stop or even when shifted out of Drive to Park or Reverse and
The ins and outs of transmission diagnostics
Are new cars harder to work on than old? It depends on who you talk to. And if old cars are deemed easier, what takes the blame for the difficulty on the new versions? You can be certain that it’s computers and electronics. Someday we’ll all be gone, but until then there’s a group of
Ford 6R140: Repairing the elusive intermittent neutral condition
The 6R140 has been in large Ford trucks since 2011 and is now considered a common unit in most shops. Our discussion today concerns the elusive intermittent neutral condition. At one particular time, this complaint was so common at one particular California utility company with a fleet of trucks that there seemed to be no
A misleading code: Finding the right solution to the right problem
In having the privilege of presenting at Worldpac’s Supplier and Training Expo in Orlando Florida earlier this year, I met a couple of instructors from the Daytona State College who attended my seminar: Beau Bosman and Casey Knecht. During my presentation, I covered an issue with an Allison 1000/2000 that had the converter clutch cycling
Transmission programming modules: When to reprogram and when to replace
Programming modules have been an essential aspect of the complete repair and service experience (Figure 1) within the automotive industry for quite some time now. Not providing this service shortchanges both the shop and the customer; yes, the repair has been performed, but the vehicle is still not working as well as it could be.
Ford 6R140 separator plate identification: How to identify changes and interchangeability
Ford introduced the 6R140 transmission, paired with the 6.7L diesel, in early 2010 for 2011 model year production. This has created confusion when trying to identify valve body components, as new model year release is usually near the end of the previous year. Valve body and separator plates have gone through numerous updates since the
10R80 gear ratio errors after rebuild
A 2018 F-150 Raptor using a 3.5L EcoBoost in front of a 10R80 transmission developed a noise at the rear of the transmission. The shop eventually diagnosed this as a rear case needle bearing failure. When road tested after repairs, the computer detected gear ratio errors immediately. This took the shop through a time-consuming process before
A Chevy Volt making noise
There is a Preliminary Information (PI) paper published by GM regarding a concern with 2011 to 2013 Chevy Volt using a 4ET50 transmission. The PI paper explains that some customers may comment on a whistle, scrape or whine type noise while driving that may be more noticeable during regenerative braking. Technicians may find this noise
