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This is a hindsight-is-perfect post for other weary pilgrims trying to find their way to certain transmission solutions.

For a 2002 Focus with SPI engine and automatic transmission with only about 80,000 miles on it, I encountered gradually worsening trans problems.

It began this way:

After driving 300 highway miles and then slowing down for some stop-and-go local driving, I found that it was beginning to shift hard, and there was also some brief slipping out of 3rd gear altogether, and also bursts of a couple seconds where it dropped down to a lower gear for a split second, then jumped back up, perhaps repeating this several times.

This then became the persistent behavior. It didn’t matter whether I was speeding up, slowing down, or at steady city speeds. I didn't have the problem cruising at highway speed.

Then it got worse. After just a couple miles of warmup, the car consistently dropped out of 3rd before slamming back into gear after a number of seconds. To avoid the slamming, for city driving I put the car in 2nd gear once it had automatically shifted into 2nd or 3rd.

To that point I didn’t have a problem cruising at highway speeds, but that changed, with split-second episodes of the shuddering behavior I describe above.

It continued to be the case that the problem didn’t appear before the car had warmed up at least a couple miles.

There was no delayed shifting, and all shifts occurred at decent shift point speeds.

The next development: It began "reliably" slipping out of O/D as well as 3rd. I also observed that after a couple miles of warmup, the 1-2 and 2-3 shifts were both clearly harder than in the first couple miles.

I had started wondering why the Check Engine light and/or Transaxle light were not lit. I finally discovered that there was no bulb in the CEL (aka “Malfunction Indicator Light” or MIL) socket! For good measure, there was also no bulb in the Brakes socket. [The previous owner whom I bought the car from 6 months prior was trying to hide something?] With those bulbs replaced, the CEL was lit all the time. Advance Auto gave me a free OBD scan which produced codes P0750 and P0755. Their descriptions:

P0750
Description: SSA solenoid circuit failure
Condition: SSA circuit failed to provide voltage drop across solenoid. Circuit open or shorted or PCM driver failure during on-board diagnostic
Symptom: No reverse gear (short) or no fourth gear (open).
Action: Refer to Pinpoint Test A.

P0755
Description: SSB solenoid circuit failure
Condition: SSB circuit failed to provide voltage drop across solenoid. Circuit open or shorted or PCM driver failure during on-board diagnostic
Symptom: Not all gears present. No converter clutch apply in third and fourth gears.
Action: Refer to Pinpoint Test A.

I replaced the SSA and SSB solenoids and changed the trans fluid and filter. (There are instructions elsewhere on how to do both jobs.) Both solenoids have the same P/N: XS4Z-7H148-AA (though what is stamped on the side of the solenoid is a similar engineering number: XS4P-7H148-AA). These run about $45 each at FordPartsOnline.com and a couple dollars more at my local dealer. If you’re not in a huge hurry get them cheaper instead via Village Ford (See their thread at http://www.focusfanatics.com/forum/showthread.php?p=6720841).

This gave me some improvement. Though the CEL/MIL was lit again, I found that I could drive in 3rd with O/D switched off at up to 50 mph, at which point the race/slam behavior would appear. If I drove with O/D on, the bad behavior would appear anywhere in the 3rd or 4th range.

Because of the 50 mph trigger, I suspected that I had a problem with torque converter control operations.

Working through some of the factory service manual's pinpoint tests such as I was able to with a multimeter, in test A8 I found an open in the transaxle vehicle harness in the wire to pin 8, which serves solenoid B and supports TCC operations. I found and fixed a broken pin 8 wire between connectors C439 and C96, which is easily accessible. (I also found and fixed another wire there that was damaged but not broken.)

Fixing the broken wire gave me back TCC operations and I no longer had any of the shuddering or racing/slamming behavior.

But I had lost 1st gear (under D or manually selected), reverse engagement was now harsh, and there was also a harsh downshift to 2nd at no throttle. All these problems were entirely new. And 4 codes were then reported: P0750, P0755, P0760 and P0765, which is "solenoid circuit failure" for solenoids A, B, C and D (but not E, which would have been P0770).

Since I had looked at and fixed all the wiring problems I could find, I then suspected the powertrain control module (PCM), which is the third possibility cited in the trouble code descriptions.

In the meantime things had degraded further again. I had the CEL/MIL and also the Powertrain Warning Light lit, and DTC's P0750, P0755, P0760, P0765 and P0770 (indicating a problem in all of the 5 solenoid circuits.)

The Powertrain Warning Light could mean several things, but one of the things it could mean is that the Emergency Operating Program is in effect. And that did correspond with driving behavior: a harsh shift into reverse, and only 3rd gear available for a forward gear.

Anyhow, with the wiring problems fixed as far I knew, I resorted to replacing the PCM (about $50 for a used one, and another $250 for the dealer to reprogram it).

But this did not fix the problems. So I was left with unhappy ponderings about whether the PCM was bad to begin with, or whether something in my car was killing PCM’s.

After a long period of mourning and driving the car around gently in limp mode (aka emergency operating program), I began a fresh inquisition.

I repeated the factory service manual’s solenoid-oriented tests, Pinpoint Test A, such as I could do them with just a multimeter. This meant skipping most tests that required a Ford scan tool. I was able to check circuits for opens, shorts, shorts to power, and certain voltages. Those tests were all clean, except that when applying voltage directly to the solenoids, I could hear SSC, SSD and SSE click (these are the PWM solenoids). But I could not hear clicking from SSA or SSB (the on/off shift solenoids).

At this point I got a lot of critical help from another thread I started at http://www.focusfanatics.com/forum/showthread.php?t=467129. I found out that SSA and SSB are normally closed, and that applying voltage should open their valves. I fitted a hose on the nipple of the solenoid, applied voltage across it, and could not blow through these solenoids, so I took that as a confirmation that SSA and SSB had been killed after I replaced them previously.

Another knowledgeable poster suggested that in addition to the Pinpoint A tests, I also install 12vdc light bulbs in lieu of the solenoids. The theory here being that a circuit can show continuity but still not be able to carry the needed current. (Imagine a case where 99 strands out of a piece of 100-strand wire are broken.)

This I did, and none of the 5 bulbs lit! What I eventually tracked down was that the pin sockets in the C96 connector had all been spread out such that they no longer made proper contact, but only enough contact to register continuity. I think someone previously working on the car had jammed electrical probes that were too large into each of those sockets.

Once I fixed C96 and reassembled everything, all the problems were fixed, and it was the end of a long odyssey!!!
 
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