Scope testing the Ford 10R80 - Transmission Digest

Scope testing the Ford 10R80

Recently, we at Certified Transmission had a chance to do some work with the Ford 10R80. We have easy access to test vehicles since our owner also owns a used car dealership. For our R&D testing we used a 2019 F-150 equipped with a 5.0L engine and the 10R80 transmission. I got to play around and do some scope testing on it.

I’m so happy that both Ford and GM had decided to move the transmission control back outside of the unit. It sure makes this kind of testing easier to accomplish.

I am sure most of you have seen the articles and tech bulletins about this unit. It utilizes six shift solenoids, a N.H. (normally high) LPC solenoid and a N.L. (normally low) TCC solenoid. The shift solenoids are what Ford refers to as CIDAS (Casting Integrated Direct Acting Solenoid), which basically means that there is no fluid flowing through them so the pintle movement acts directly on a valve. The scope captures referenced below are at a sample rate of 10us (micro seconds).

I had a Yokogawa scope connected to all eight solenoids and a 0-500 PSI Pico pressure transducer connected to the line pressure service port. What I ended up with was PWM (pulse width modulation) solenoid control I have never seen before. Neither the duty cycle nor the frequency remained consistent. We have all seen normal square wave patterns with variable PWM control, but I had never seen what a 10R80 pattern looks like. Obviously, I am not an electrical engineer, just a transmission guy, so the best way I could describe it is if you had a rolling TCC surge on a 4L60E and the duty cycle kept changing to try to accommodate for the slip.

Figure 1 shows a good example of shift solenoid operation in ninth gear. SSA and SSD are clearly off (although SSA has a high spike about every 5ms), while SSB, SSC, SSE and SSF are all on but not in a manner we are used to seeing. Focusing on SSB, we see that the duty cycle does change a bit, but looking at the Hz is where you can see the big difference.

Figure 1.

The scope software has a very good math function which is the only way you can see frequency. At different points on the screen, the Hz change from about 625Hz to 7150Hz; the higher Hz occurs right after the longer initial turn-on. All the data on the screen is scaled at 100ms.

The TCC solenoid operation is the most consistent, probably because it is more like a traditional solenoid we are used to seeing. Cruising with light load, duty cycle varies between 35 and 45%, and Hz between 2.6KHz and 3.5KHz.

I was hoping to provide some line pressure to duty cycle specs, but even at a steady line pressure reading the Hz, duty cycles change so much that it is difficult to put into a format that would make any sense. However, I do want to bring up some discrepancies I see with service information that is out there. (See Figure 2).

Figure 2.

Reverse WOT stall spec is 240. When at full stall in R the EPC shuts off and the pressure looks like a sine wave between 239 and 305 PSI, even when the solenoid turns on again. This surge continues until you start to lift off the throttle. This being said, your pressure gauge is going to be “spiky.” (See Figure 3).

Figure 3.

I am going to say this is normal as it exhibited this behavior with both a used and brand-new valve body. On the other end the charts I have seen all specs showing 90 PSI at idle in all ranges, but what I saw in reality was 72-75 at idle in all ranges.

On the Park to Drive garage shift we have some conflicting info from the solenoid application chart.

The chart in Figure 4 shows SSB is on in Neutral and turns off when D1 is commanded. I don’t really see that on the scope capture in Figure 5.

Figure 4.
Figure 5.

SSE turns on with a long pulse “high,” and then starts regulating. Park to Reverse operates similarly when SSF is turning on. The difference that I see with this one is with SSD. (See Figure 6).

Figure 6.

Where the chart shows that SSD is on in both Park and Reverse, actual monitoring shows it changing from a slow 77Hz/12% positive duty cycle to a fast 2.2727Khz/50% duty cycle. It is not just as simple as an on/off solenoid chart, and I think these charts can be a bit deceiving at first glance. This is especially true when diagnosing with a DVOM. You think the solenoid is off according to the chart, but you still see voltage on your meter. This could lead you down the wrong path if you are looking at solenoid activity. On any of these newer units, you must use a scope for this testing.

One last thing I found quite interesting: during every up-shift event (except for 3-4), line pressure went to max command in forward ranges at 240 PSI. The scope shows a first through tenth 0 to 75 MPH run that took 50 seconds.

Read more stories in our R&R Tech series here.

Chris Adams started with Certified Transmission in 1986 as an R&R technician, and currently works as Diagnostic Trainer and Lead Diagnostician. His current duties involve training and advising the company’s retail diagnosticians, as well as assisting in the research and development of its remanufactured products. He also holds ASE Master and L1 certifications.

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