Issue Summary:
- General Motors electronic transmissions can experience a wide variety of complaints related to program parameters installed in the vehicle’s computer at the time of manufacture.
- PCMs in some 1996 and 1997 Taurus and Sable models equipped with 3.0-liter 12-valve engines have been reprogrammed to eliminate complaints of engine surge or engine miss at vehicle speeds between 45 and 60 mph while the vehicle was still under factory warranty.
- Before or after overhaul, 1995-2002 Ford Motor Co. vehicles equipped with 4R44E/55E or 5R44E/55E transmissions may exhibit soft or flared shifts and multiple gear-ratio errors.
Since 1996, the number of service bulletins from car manufacturers on reflashing computers to desensitize code setting, resolve a drivability complaint or rectify any type of concern has increased dramatically.
A code for the transmission-fluid temperature sensor or a turbine-shaft speed sensor may, for example, be resolved by simply reflashing the computer. This obviously is an easy and inexpensive repair for the dealer, and although a factory bulletin might offer its own diagnostic procedures before a reflash would be considered, in many instances the technician would make it the very first step. If the reflash didn’t fix it, replacing the part in question usually would be the next action taken. If neither of these options worked, either the computer would be replaced or actual testing with the use of a DVOM and/or scan tool would be finally employed.
The independent repair facility is not so easily afforded this luxury of reflashing or parts replacement, especially since the independent facility works on vehicles from a variety of manufacturers. As a result, in most instances proper diagnosis starts with a scan tool and DVOM. Restoring power supplies and/or grounds, or replacing sensors, wires or solenoids often resolves the problem. In other instances, diagnosis eventually leads the technician to determine that a computer is suspect. At this stage the question that is often asked is, “Should I replace the computer or should I have it flashed?”
General Motors should be commended for making this question somewhat easily answerable in regard to its vehicles. A free service that GM has provided is a Web site (http://calid.gm.com/vci/) that enables one to enter the 17-digit VIN for 1993 and newer vehicles. After the entry, it reports back as to which types of symptoms are resolved with a specific reflash procedure or by a PROM update. By comparing this list with the symptoms of the vehicle in the shop, the technician can determine whether the new PROM or reflash will resolve the problem. If the symptoms do not match any one on the list, chances are a reflash or PROM exchange will not resolve the vehicle’s problem. This would mean the next step is to replace the computer or PROM (older computers with an actual PROM will need to have a PROM replacement; computers that are flashable – in other words, have an EPROM – will need to be replaced completely).
All other manufacturers provide this information in bulletin form, making it difficult for the independent repair facility to know all the symptoms that the flash procedures cure – unless, of course, the repair facility is prepared to invest money into sources that provide these bulletins, such as Alldata (800-697-2533) or Techfacts (610-459-0283). Knowing which symptoms are being resolved with reflash procedures is a different type of tool that can provide an edge in the diagnostic procedure.
The complaints are far too varied to list individually; they could be drivability related or transmission related. Transmission-related complaints could include concerns with line pressure, shift scheduling or shift adaptation, or ways to correct stalling, surging or TCC strategies.
Program parameters installed in the vehicle’s computer at the time of manufacture may be set to be sensitive to various operations in order to meet certain government demands. Once the vehicle is “broken in,” these parameters can cause customer complaints such as those listed above, at which time these parameters need to be desensitized in order to cure the customer complaints.
Another reason is that it is more cost effective to reflash the vehicle’s computer to allow it to tolerate a sensor signal that would, in the past, require sensor replacement.
1. Be sure to perform the necessary diagnostic procedures to ensure that reprogramming will cure the complaint.
2. Gain access to complete information about the update revision by going to the GM Web site http://calid.gm.com/vci, which explains what the revision does and lists any factory TSBs that relate to this revision.
3. It is critical to match the revision to the complaint, because once the reflash is complete, it cannot be reversed. This is due to the nature of the reprogramming procedure, which begins by erasing the old program. Once a revision is chosen, all calibration changes in that revision will be downloaded; an individual calibration cannot be selected.
4. Since some type of computer hardware is required, make certain all power-saving and screen-saver devices are turned off so as not to interrupt the reprogramming process.
5. There are two ways to reprogram: the “pass-through” method and the “download” method.
- The download method requires that the updated program be downloaded from the shop computer into the scan tool. The scan tool then must be taken to the vehicle and connected to the diagnostic connector to download the new program into the vehicle computer.
- The pass-through method requires the updated program to be taken from the shop’s computer and passed through the scan tool and into the vehicle computer. In each method the updated programs are provided by General Motors “Service Programming System” or “Expertec” CD program, supplied by Vetronix Corp., maker of the Tech 2 and Mastertech scan tools. One of these scan tools will be required to perform the reprogramming.
6. It is strongly recommended that the computer be reprogrammed while it is in the vehicle rather than “off board,” which requires expensive equipment that even most dealers don’t have.
7. System voltage MUST be maintained and held steady between 12 and 14 volts. This is accomplished through the use of a separate regulated voltage supply device. DO NOT USE A BATTERY CHARGER! If voltage is allowed to drop or the scan-tool connection at the diagnostic connector is broken during data transfer, the vehicle computer does not know what to do with an incomplete program and will keep trying to complete the download without success. This constant loop of download attempts cannot be stopped and will require replacement of the vehicle computer.
Reprogramming With the Vetronix Mastertech and the Service Programming System (SPS):
Remember to turn the ignition off before disconnecting anything.
You can contact Vetronix Corp. at 800-321-4889 or go towww.vetronix.com.
The vehicle may have come into the shop for repairs not related to this complaint. During the road test either before or after repairs, the scan tool indicates zero TCC duty cycle and no TCC apply. Strangely enough, no codes are stored for a TCC-related problem; in fact, after repairs no codes of any kind are stored, nor is any MIL illuminated, and the transmission works perfectly.
Some 1996 and 1997 Taurus and Sable models equipped with 3.0-liter 12-valve engines had complaints of engine surge or engine miss at vehicle speeds between 45 and 60 mph (72 to 96 km/h) while still under factory warranty. Ford’s cure for this complaint was to reflash the PCM to eliminate TCC operation until after 48 mph or when the engine-coolant temperature reaches 240° F or higher.
If the PCM has been reprogrammed to eliminate TCC operation, NO repairs are required. One of the clues to help determine that TCC was eliminated would be a door-jamb sticker such as the one in Figure 8 with factory TSB 98-13-7 written on it, which explains the reasons and actions that prompted the need to eliminate TCC operation.
Another clue would be a sticker under the hood that may have on it nothing more than a Ford part number, which is the part number for the new calibration that eliminates TCC operation. The chart in Figure 9 illustrates the part numbers for TCC-elimination calibration that would appear on the underhood sticker.
Before or after overhaul, 1995-2002 vehicles equipped with the 4R44E/55E or 5R44E/55E transmissions may exhibit soft or flared shifts as well as multiple gear-ratio errors.
The cause may be insufficient pressure rise.
To correct this condition, install the “throttle kit” shown in Figure 10. This kit requires the use of a spacer plate with the EPC blow-off hole eliminated, per Ford Motor Co. bulletin number 02-13-8, as shown in Figure 10.
- Throttle kit (FORD part no.) ……1L5Z-7M203-JB
- Spacer plate (Ford part no.)………See Figure 11
October 2003 Issue
Volume 20, No. 10
- The Reflash Corner
- Automotive Computer Reprogramming: General Motors Procedures
- 1996-97 Ford Taurus/Mercury Sable: No TCC Apply
- Ford 4R44E/55E and 5R44E/55E: Flared Shifts and/or Gear-Ratio-Error Codes