Re: 4L60E transmission (long)


Posted by Traveler on May 19, 01 at 22:39:00:

In Reply to: 4L60E transmission posted by Nancy on May 19, 01 at 19:17:34:

You didn't say wat year. If it's a '96 or '97, the problem is expected and the following TSB is the fix, or one of the fixes.

96 Transmission TSB:
AUTOMATIC TRANSMISSION 1-2 AND OR 2-3 UPSHIFT SLIP/FLARE #66-71-04
SUBJECT: AUTOMATIC TRANSMISSION 1-2 AND/OR 2-3 UPSHIFT
SLIP/FLARE, NO 3RD OR 4TH GEAR, LAUNCH SHUDDER,
DTC P1870 (REVISE VCM WIRING)
MODELS: 1996 CHEVROLET AND GMC C/K, S/T, M/L, G1, G2 AND P3 MODELS
1996 OLDSMOBILE BRAVADA
WITH VCM AND 4L60-E (M30) OR 4L80-E (MT1)
AUTOMATIC TRANSMISSION
CONDITION:
SOME OWNERS MAY COMMENT THAT THE AUTOMATIC TRANSMISSION HAS
EITHER A
SLIP OR FLARE ON THE 1-2 AND/OR 2-3 UPSHIFT, OR NO 3RD OR
4TH GEAR, OR LAUNCH SHUDDER. DTC P1870 MAY ALSO BE STORED
IN THE VCM.
CAUSE:
A POOR INTERNAL GROUND BETWEEN THE TWO CIRCUIT BOARDS OF
THE VCM CAN CAUSE THE VCM TO COMMAND ERRATIC LINE PRESSURE
AT THE PRESSURE CONTROL SOLENOIDS (PCS).
CORRECTION:
USING HARNESS JUMPER WIRE AND INSTRUCTION KIT, P/N 12167310,
REVISE THE WIRING HARNESS AT THE VCM CONNECTOR.
CORRECTIONS WERE MADE TO THE VCM BEGINNING 2/14/96. THE
CORRECTED VCM'S ARE IDENTIFIED WITH SERVICE NUMBER 16244210
ON THE VCM IDENTIFICATION LABEL.
SERVICE PROCEDURE
THE FOLLOWING IS A SUMMARY OF THE INSTRUCTIONS INCLUDED
WITH THE SERVICE KIT:
1. REMOVE THE NEGATIVE TERMINAL FROM THE BATTERY.
2. MOVE THE WIRE LOCATED AT CONNECTOR J3
(WHITE/GRAY/CLEAR), PIN 18 TO CONNECTOR J1 (BLUE), PIN 23.
3. INSTALL THE JUMPER WIRE BETWEEN CONNECTOR J2 (RED),
PIN 26 AND CONNECTOR J3 (WHITE/GRAY/CLEAR), PIN 18.
4. INSTALL THE TAG INCLUDED IN THE KIT AROUND THE VCM
WIRING HARNESS. THIS TAG NOTES THAT THE WIRING HARNESS HAS
BEEN MODIFIED.
5. RECONNECT THE NEGATIVE BATTERY TERMINAL.
ROAD TEST TO VERIFY THAT THE CONDITION HAS BEEN
CORRECTED.
IF ANY OF THE FOLLOWING CONDITIONS ARE NOTED, THE
TRANSMISSION SHOULD BE REPLACED, OR FOR CANADIAN
DEALERS, REPAIRED.
-TRANSMISSION FLUID OXIDATION OR EXCESSIVE SEDIMENT.
-TRANSMISSION SLIP OR FLARE AFTER THIS SERVICE FIX IS
PERFORMED.
-DTC P1870 IS STORED ON A 4L60-E (M30).
THE FOLLOWING TOOLS ARE AVAILABLE FROM KENT-MOORE (1-800-
345-2233) FOR USE IN REMOVING AND RELOCATING THE VCM WIRES:
-J41758 TERMINAL TOOL: USED TO REMOVE THE WIRE FROM THE VCM
CONNECTOR.
-J41759 PUNCH: USED TO PUNCH A NEW HOLE THROUGH THE
CONNECTOR SEAL.
PARTS INFORMATION
P/N DESCRIPTION QTY
12167310 HARNESS JUMPER WIRE KIT 1

- - - - - -

Here is general info on what ailments the 4L60E has:

General Motors 4L60-E Transmission
Electronic Problems / Technical Information

Illustrations
Figure 1
Figure 2
Figure 3

This article will discuss some of the common performance and durability problems related to the very popular 4L60-E transmission found in many General Motors vehicles. In the last several years, there has been and continues to be a strong consumer demand for Sport Utility Vehicles (SUVs) and pickup trucks in both 4X2 and 4X4 configurations.
Customers purchase these vehicles in place of automobiles for a variety of reasons. Some owners like the convenience of having a vehicle that can carry or tow extra weight when they go camping, boating, and so forth. Some use their vehicles for household chores, such as picking up building materials for a weekend project. Others like having that extra feeling of security when driving in cold weather climates where winter brings snow and ice.

The point is that these vehicles generally see more extreme duty driving than the luxury automobiles they replaced. On that basis, shops should pay careful attention to repair techniques to avoid premature failures and costly comebacks. Superior parts quality is very important, as is anticipating what the vehicle might be used for after you've performed minor or major repairs.

Pressure Rise Control Problems

As with any modern automatic transmission, performance, durability and longevity begin with a sound pressure control system. Delayed or underactive pressure rise can cause a host of problems, ranging from long or soft shifts to premature friction failures. Not performing post repair pressure checks can easily turn a relatively minor rework into a very costly comeback. As such, you should be aware of some common problems that can adversely affect your shop's reputation and bottom line.

Pump condition is crucial. Even slight wear can cause a lower-than-expected pressure, especially when the transmission shifts into a higher range and the TCC applies, since the engine and pump speed will be at a relatively low RPM. The low RPM coupled with hot, thin ATF taxes even a sound pump, while a worn pump will usually lead to premature failures.

With a sound pump, free flow sump filter, and an electronic engine load system functioning properly, delayed or underactive pressure rise can be caused by a fault in the Vehicle Control Module (VCM) circuit responsible for signaling the Pressure Control Solenoid (PCS). Specifically, the VCM (figure 1) can have a poor internal ground wire that interconnects the two internal circuit boards.

It isn't necessary to replace the VCM for this condition: General Motors has released part number 12167310 service package, which consists of a wire and instruction sheet. Although at first glance the instructions may look quite involved, installing the wire is simple and doesn't take very long.

You should check every 1995-up 4L60-E for this service kit, since pressure rise control problems may develop after your overhaul, and as a result, come back to haunt you. There's also no reason why you can't charge the customer for the service package and installation labor. When you explain the benefits to the customer, the customer will seldom, if ever, question its benefit and additional cost. It also displays your advanced technical competence to the customer for staying abreast of possible or pending problems that are common to the application you're working on.

Other causes for delayed or underactive pressure rise can be traced to electronic input devices such as the TPS, MAF sensor, or any input control device that senses engine load. Because of the base design of a TPS (sweeping potentiometer), it is a very active device. Through continual testing, we have found that the TPS signal begins to degrade significantly after about 50,000 miles. The same conditions of degraded signal response are also true of the PCS.

Pressure rise control problems can exist even after all of these items have been checked and repaired. The PCS filter screen attached to the valve body separator plate can collapse under high load conditions, restricting or shutting off signal feed oil. You should replace the PCS filter screen during all major repairs or valve body services. Remember, no modern automatic transmission can perform properly or have adequate durability and long life if the pressure control system isn't working properly!

Solenoid Operational Problems (Electronic)

Anyone who's worked on the 4L60-E transmission has, at one time or another, encountered multiple solenoid faults. These faults usually set DTCs 66, 67, 81, 82 and 83. Although a failed or failing solenoid can cause a DTC to set, these multiple solenoid DTCs are usually caused by a failed transmission circuit fuse (open circuit), or a failed ignition switch; specifically, circuit E that provides battery voltage to the solenoids. For this part of the discussion, let's focus on ignition switch failure, which is more common than some technicians realize.

With the key on, engine running, a battery voltage signal is sent to the solenoids through pin E of the transmission harness connector. If battery voltage isn't present, the solenoids can't power up: Default operation occurs, and multiple DTCs set.

To address this problem, replace the ignition switch. The labor time required averages 1.5 2.0 hours, and the retail cost of ignition switch is about $155.00.

Solenoid Operational Problems (Hydraulic / Mechanical)

Shift scheduling problems can occur both before and after overhaul. No upshifts, wrong gear starts, occasionally skips a gear etc., can be caused by solenoid internal faults. Failure of the solenoid to open or close quickly and efficiently can also result in extended shifts; here's why:

With any modern electronically-controlled transmission that uses solenoids to control shift valves, the valve must move quickly for the feed pressure to reach the friction element. If the shift valve moves slowly due to a solenoid fault or restrictions, the shift can be extended, because the slow-acting shift valve is causing a friction element apply delay. So you should consider whether or not you want to reuse a solenoid that has been in operation in excess of 50,000 miles. At the very least, the solenoids should be evaluated using one of the many solenoid test tools available.

Most shift solenoids are termed hydraulic / mechanical actuators. The term is quite accurate since the solenoids control fluid pressures mechanically by opening or closing some type of valve--usually a small, ball-type valve. The 4L60-E and several other units have experienced wrong gear starts, loss of shifts, etc., because the pressure feeding the solenoid is inadequate. Take a look at the feed passages for the shift solenoids (figure 2). Separator plate orifices A and D feed the solenoids (figure 3). Some plates have orifices that don't appear to be quite round. Whether or not the manufacturing process causes this is irrelevant. What is relevant is that you must make sure these two orifices measure 0.031" 0.035".

Caution: Bigger isn't always better! Opening the solenoid feed orifices beyond 0.035" can easily lead to solenoid feed flooding. You must decide whether to make this orifice size change a rebuild procedure. But you should always check the orifices with a drill bit, since it's a lot easier to Fix It Right the First Time before assembling the transmission. Also, when you're installing the valve body gaskets, be sure to align the gaskets accurately: A mispositioned gasket can restrict the solenoid feed orifices in the plate. It doesn't take a lot and when you experience mispositioned gaskets one time, you'll realize the benefit of using valve body alignment studs that you can make from a few extra valve body attaching bolts.

Take another look at the filter shown in the upper left corner (figure 2). This is the shift solenoid feed filter, located on the separator plate. If the transmission failure generated lots of debris, this filter can easily become restricted. The feed fluid must pass freely through this filter, so you can actually experience restricted feed to the solenoids even though the two feed orifices in the plate are the correct size. Since this filter can be difficult to wash thoroughly, you should replace it during overhaul or valve body service. Some of the overhaul kit repackagers even include the filter in their kits.

Odds and Ends

DTCs and subsequent failures related to the 32 solenoid can be caused by a faulty solenoid, solenoid mismatch, loose solenoid connectors, and especially transmission harness connector problems. A transmission harness connector repair kit is readily available from your parts distributor.

TCC related DTCs and subsequent failures including an overheated TCC friction ring can be caused by a worn TCC bore in the valve body. Several aftermarket manufacturers have developed parts to address this problem. These parts are available through your local parts distributor.

An external transmission cooler is a great way to improve durability and longevity.

Leaks from the pump area usually indicate the pump bushing has seized or is moving. Small, crater-like impressions on the bushing surface indicate electrical arcing. Make sure all ground connections are clean and secure. For added protection, install redundant ground straps. If the bushing appears to have moved, check the bushing area of the pump body carefully for signs of cracking. The cracks can be small, so hold the pump body up to a strong light for careful inspection.

Important: The calibration changes and modifications discussed throughout this article pertain to the original factory calibration. If you are installing one of the commercial valve body kits, use the calibration information that is furnished in the kit's instructions. Be careful intermixing calibration specifications and, if you are given a choice of spring tensions, orifice sizes, etc., stay on the conservative side. Firm, bangy engagements and shifts do nothing for durability, detract from overall performance, and can cause customer complaints.

The 4L60-E has undergone many parts design changes in recent years. Malfunctions and total failures can easily result from mismatched or intermixed parts. Parts such as pumps, solenoids, separator plates, valve bodies, etc., must be matched carefully when replacing any of these components. ATRA and other Technical Support Services have released a lot of information regarding these changes. Always have the parts identification information readily available for reference. The information will avoid unnecessary delivery delays and expensive comebacks.



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