New vehicles more complicated, but more reliable

by Jim Kerr . Apr 13 2017
SuppliedFord’s 2017 F-150 trucks are now available with the all-new 3.5-litre EcoBoost engine and 10-speed transmission.


Ford’s 2017 F-150 trucks are now available with the all-new 3.5-litre EcoBoost engine and 10-speed transmission.

QUESTION: Regarding the new 10-speed Ford transmission, would these be repairable or throwaway products given the mechanics of these units? I have never had to have an automatic transmission repaired in the 45-plus years I have been driving. Good luck or regularly servicing the unit may have been the reason. However, the mechanics of vehicles is becoming much more complicated. Are they better?

— Mike

Answer: The vehicles are becoming more complicated, both electronically and mechanically, but they are also getting more reliable. Many manufacturers are building transmissions with six-, seven-, eight- and nine-speed automatic transmissions, and now Ford (and soon GM) with 10-speed transmissions. To get the additional gear ranges, another set of planetary gears are typically added to the design and additional clutches are connected to hold or turn parts of the gear sets. Electronic controls have made the mechanical parts last longer because the computer is capable of making much better shifts than the older, strictly mechanical, systems.

For example, during a shift, the computer can decrease engine torque, so the transmission clutches can apply with less slipping. It can also control the transmission hydraulic pressures to the clutch release and apply rates to give the desired shift feel. During slow acceleration, most drivers want a smooth shift, but if you are shifting at wide-open throttle, you may want a firm shift to give you the performance you desire from the vehicle. On many vehicles, the computer can also control engine speed during a shift, matching the rotating speed of parts during the apply so there is less stress and wear on parts. All this adds up to longer parts life and reliability.

The other place I have seen big improvements is in electrical wiring and connectors. They seal better, so there is less chance of corrosion and failure. Over the years, the trend is to replace more complete assemblies rather than repair individual components, but the overall reliability and life of those assemblies have improved. It is very common now to see vehicles with 300,000 to 400,000 kilometres on them and mechanically still operating well.

Question: We have a 2014 Toyota Matrix with an automatic transmission and 1.8-litre engine. It now has 75,000 km, but at 65,000 km, it started banging into lower gear when going up a hill on cruise control. It doesn’t do it all the time.

It shows nothing on the computer and no lights come on the dashboard when it happens. Fluid levels and oil colours are fine.

Sometimes it is louder than other times and sometimes it is so bad that you look in the mirror to see if there are parts on the road. Can you help?

— David

Answer: The transmission shifting in your Matrix is computer controlled, where the computer operates an electric solenoid and the solenoid either holds or releases oil pressure on a mechanical control valve. The computer monitors the electrical circuits and if there was a problem with the wiring or the solenoid, it should turn on the check engine light on the dash.

There could still be an electrical problem with the transmission temperature circuit to the computer. If the transmission temperature is reported cold, the computer increases fluid pressure inside the transmission to make the thicker fluid flow in the right time frames. If the temperature is reported falsely, then the pressure may be high but the fluid is thin and flows too quickly, causing a harsh shift.

I do suspect, however, that the problem may be mechanical. The transmission has a shift-timing solenoid that controls hydraulic operation of the second-band apply and release. If the mechanical valve that controls this band is sticking, then the shifts may be harsh, and, if the band is applied too soon, it can cause a binding of the gears that could create a loud and harsh bang.

Unfortunately, this type of problem isn’t easy to fix at home. The first step would be to test the transmission oil pressure to make sure it is correct and not too high. Then the valve body may have to be removed from the transmission and the mechanical valve inspected to see if it is sticking. Many repair shops have scanners that can command the operation of the solenoids while driving while the car is raised on a hoist. This may help with the diagnosis, but it is something that few of us have at home.