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Where is Shift Solenoid Valve E?

Thursday, September 10, 2015 - 07:00
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A 2007 Acura MDX 3.7L V6 using a BYFA 5 speed automatic transmission comes in to your shop sporting a DTC P1744. The definition of this code is as follows: Problem in Shift Control System; Shift Valve E Stuck ON. Many transmissions today refer to solenoids as valves and most do not have an actual valve in the valve body identified by just one letter. If it does have valve names using a letter, it typically refers to the solenoid that operates the valve. As a result, the reaction to this code is to look for Shift Solenoid Valve E. But when you do, you discover that this transmission contains seven solenoids. Pressure Control Solenoid Valves A, B and C and Shift Solenoid Valves A, B, C and D. So where is E? You’ll never find it because there is no such solenoid.

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Figure 1
Figure 2
Figure 3

Acura provides the following general description for DTC P1744:

Shift valve E is incorporated in the control circuit of the transmission. It is controlled by pressure from shift solenoid valve B, and it is locked by the line pressure. It switches off when shift solenoid valve B turns off and shift solenoid valve A turns on (figure 1).

The PCM monitors the mainshaft speed and the countershaft speed at the gear change determined by the shift schedule. When an improper gear ratio is output compared to the predetermined gear change mode, a shift valve E ON failure is detected and a DTC is stored.

Simply explained, shift valve E keeps the valve in the un-stroked (closed) position. This valve needs to stay in the closed position for 1st, 2nd and 3rd gear. Shift Solenoid A assists the spring in keeping the valve closed in 2nd and 3rd gear. Shift solenoid B strokes the valve in 4th and 5th gear. If the valve does not stroke, 5th gear will be un-attainable. If the valve is stuck in the stroked position, the vehicle will take off in 5th gear instead of 1st.  3rd gear is affected also should this valve be stuck in the stroked position.

The most common cause producing this code is a stuck shift valve E located in the secondary valve body next to the manual valve (figure 2). Sometimes Shift Solenoid Valve B mechanically fails (figure 3). When this solenoid is OFF, it applies pressure to its respective valves. Shift Valve E is one of them. When this solenoid turns ON, it blocks pressure from stroking its valves. Shift Solenoid Valve A works opposite. In fact, Shift Solenoid Valves B and C are Normally Applied Solenoids while Shift Solenoid Valves A and D are Normally Vented Solenoids. Care must be taken that they are installed in there correct location and that they are plugged in correctly.

The Yellow wire connector goes to shift solenoid valve A.

The Green wire connector goes to shift solenoid valve C.

The Red wire connector goes to shift solenoid valve B.

The Orange wire connector goes to shift solenoid valve D.

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