The Secret Code - Transmission Digest

The Secret Code

When an electrical failure or some type of system failure occurs, prompting the computer to initiate a programmed failsafe condition for the transmission, it is essential for the technician to have the ability to obtain the diagnostic service code that accompanies the failsafe condition. Not having the ability to obtain this code or codes in essence causes the technician to be blind.

The Secret Code

Technically Speaking

Subject: Obtaining diagnostic service codes
Units: Five-speeds
Vehicle Application: Honda/Acura
Essential Reading: Diagnostician
Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor

Technically Speaking

  • Subject: Obtaining diagnostic service codes
  • Units: Five-speeds
  • Vehicle Application: Honda/Acura
  • Essential Reading: Diagnostician
  • Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor

When an electrical failure or some type of system failure occurs, prompting the computer to initiate a programmed failsafe condition for the transmission, it is essential for the technician to have the ability to obtain the diagnostic service code that accompanies the failsafe condition. Not having the ability to obtain this code or codes in essence causes the technician to be blind.

Where does one begin diagnosing a problem with no idea where to start looking? Dropping the pan (if there is one to drop) to do a visual of the mechanical condition as well as a cursory overview of all related wiring is at best a beginning. But to know that one or more codes are stored yet not be able to obtain them with the shop’s scan tool raises the frustration level even higher.

Such a scenario seems to occur with Honda and Acura vehicles equipped with five-speed automatic transmissions. The D or D5 lamp will be blinking, indicating a code or codes are present, yet when the PCM is scanned for codes none are found.

Fortunately, Acura and Honda vehicles allow the technician to put the PCM into the Service Check Signal Mode by grounding terminal 1 or 9 in the OBD-II data-link connector (DLC). By doing so, the technician can flash out the “secret codes” lurking in the PCM.

In most instances there will be a brown wire in terminal 9. In other instances this wire will be in terminal 1, and terminal 9 will be empty (Figure 1). Once this wire is grounded and the ignition is turned to the on position with the engine off, codes can be retrieved via a flashing D/D5 lamp. The long flashes are the first digit of the code and the short flashes are the second digit. If a code below the number 10 is stored, it will be all short flashes.

The chart in Figure 2 provides the two-digit codes that can be obtained.

Two other points to mention here: If the MIL is illuminated, engine codes will always be displayed first, followed by the D/D5 light flashing the transmission codes stored.

Second, you may have noticed that the chart in Figure 2 has a third digit. Some scan tools have the ability to put the PCM into SCS mode through the tool itself. In these cases, the scan tool will display the two-digit trouble code as well as a third digit that indicates the nature of the failure, such as a circuit high or circuit low fault.

You May Also Like

Sherlock Holmes Approach to an AB60 No-Move Situation

The effectiveness in diagnosing automatic transmission malfunctions is an art form. Although there are similarities among the wide varieties of transmissions on the road, each transmission has its own peculiarities. Aside from having mechanical, hydraulic, and electrical hardware systems to contend with, software/programming issues and various vehicle platforms make diagnostics much more difficult.  Using scopes provides

ab60

The effectiveness in diagnosing automatic transmission malfunctions is an art form. Although there are similarities among the wide varieties of transmissions on the road, each transmission has its own peculiarities. Aside from having mechanical, hydraulic, and electrical hardware systems to contend with, software/programming issues and various vehicle platforms make diagnostics much more difficult. 

GM 6T40 Pump Identification Guide

The 6T40 was introduced in 2008 for General Motors front-wheel-drive cars in the Chevrolet Malibu and has gone through several changes throughout its three generations, specifically in the pump area. The 6T40 is closely related to the more lightweight 6T30 and the heavier duty 6T45 and 6T50. Generation one started phasing out during the 2012

Seeing the Forest AND the Trees

They say that the proverbial phrase “I couldn’t see the forest for the trees” means that a person or organization cannot see the big picture because it focuses too much on the details. Related Articles – 4L60E Harsh 1-2 Shift – TASC Force Tips: Diagnosing 8L45 & 8L90 Shift Complaints – TASC Force Tips: Hydraulics

The Manifold Pipeway

The Honda six-speed transmission has been on the bench of many specialty shops for one reason or another (figure 1). But, for those of you who have yet to lay your hands on one, mounted on the upper side of the unit is one of the largest, if not the largest solenoid and pressure switch

8L90 Vacuum Testing

Below are the diagrams for vacuum testing GM 8L90 transmissions. Note: OE valves are shown in rest position and should be tested in rest position unless otherwise indicated. Test locations are pointed to with an arrow. Springs are not shown for visual clarity. A low vacuum reading indicates wear. For specific vacuum test information, refer

Other Posts

Sometimes, a diagnostic code is all you need

With ATSG having the opportunity to help shops solve problems, sometimes we get faced with some real doozies. A shop will call and give us a laundry list of DTCs, leaving us to think someone must have a bulkhead connector unplugged. We then go through the arduous task of deciding which codes prompted other codes

10L80 and 10R80 pump gear differences

You may have seen an article in the August 2023 issue of Transmission Digest called “GM 10L80: A new kind of pump noise,” which goes over how the front cover housing in the 10L80 is fitted with a converter drive gear and idler gear. The idler gear drives the pump’s driven gear, and is press

Spotting different 68RFE designs through the years to avoid issues

The Chrysler 68RFE has had several changes through the years. Its four-speed predecessor began with a noisy solenoid pack identified by a black colored pass-through case connector (seen in Figure 1).  Related Articles – Going the extra mile: Proving your transmission repair suspicions – Diagnosing Ford 10R60, 10R80 and 10R140 series speed sensor issues – Jatco JF613E

Sometimes, you should sweat the small stuff

It’s a common phrase: There may have been a time when you worried about something, and someone who knew what you are going through said, “Hey, don’t sweat the small stuff.” Sometimes, this may be good advice. But other times, it may be wise to handle the small stuff before it becomes bigger “stuff.”  Related