Most fleets have a PM schedule. What most fleets don’t have is a PM schedule that runs the way it’s supposed to.
The interval is set. The due dates are in the system, or on the whiteboard, or in a spreadsheet. But somewhere between “scheduled” and “done,” things go sideways. A driver doesn’t bring the truck in. A tech gets pulled onto something urgent. A vehicle goes 3,000 miles past its oil change before anyone notices. And the next time it breaks down on the road, nobody is entirely surprised.
A PM schedule that your team will actually follow isn’t just a list of intervals. It’s a set of triggers, responsibilities, and checkpoints that make the work happen, whether or not someone remembers to ask.
Here’s how to build one.
Mileage is the most common PM trigger, and for over-the-road trucks, it’s often the right one. But it’s not the only one, and relying on it exclusively creates gaps.
A vehicle that sits for three months still needs its fluids checked. A piece of equipment that runs 12 hours a day accumulates engine hours far faster than road miles. A refrigerated trailer has compressor service intervals that have nothing to do with how far it’s traveled.
Before you set intervals, get clear on what’s actually driving wear on each asset type in your fleet:
For most fleets, the answer is a combination. Your PM schedule should reflect that. If your system can only handle mileage-based triggers, you’re going to have calendar-based tasks fall through the cracks.
Manufacturer maintenance schedules exist for a reason. They represent the minimum service your equipment needs to perform as designed. They’re also written for average operating conditions, which is not what most fleet vehicles see.
If your trucks run long hauls in extreme heat, your cooling system service intervals should be shorter than the OEM spec. If your vehicles operate in dusty or off-road conditions, air filter intervals may need to be cut in half. If you’re running stop-and-go urban routes, your brake wear is going to outpace what the manual assumes.
The OEM schedule gives you a starting point. Your operating environment and your maintenance history tell you where to tighten it. Squarerigger's integration with MOTOR Information Systems pulls OEM PM schedules directly into the platform using your vehicle's VIN, so the manufacturer's intervals are already loaded when you set up an asset, without manual lookup or data entry. That gives you an accurate baseline to work from, and a documented starting point when you decide to adjust it for your operating conditions.
Pull your repair records for the last 12–24 months. If you’re seeing a pattern such as brake replacements consistently coming in early, cooling issues clustering in summer, tire wear ahead of schedule, that pattern is your data telling you the interval is wrong. Adjust accordingly and track whether the pattern changes.
This is where most PM programs break down, and it has nothing to do with whether the intervals are right.
A PM is scheduled. The vehicle is due. But the driver is running a load and won’t be back until Thursday. By Thursday, something more urgent has come in. The service gets pushed to next week. Next week becomes next month. And by the time that vehicle finally rolls into the shop, it’s overdue on three PMs, and you’re doing triage instead of prevention.
There are a few things that consistently close this gap:
Notify before the vehicle is due, not after. If your process depends on someone catching an overdue PM, you’re already behind. An alert at 80% of the interval gives you time to schedule the vehicle before it’s overdue and before the driver is committed to another run, before the shop is slammed.
Put someone in charge of PM completion, not just PM scheduling. Knowing a vehicle is due is different from ensuring it gets serviced. Someone needs to own that follow-through, coordinating with dispatch on availability, confirming the vehicle came in, and closing the loop when the work is done.
Track compliance, not just completion. Completion tells you the service happened. Compliance tells you whether it happened on time. A fleet running at 60% PM compliance, meaning 40% of PMs are being done late, has a fundamentally different risk profile than a fleet at 95%, even if both eventually get everything done.
Driver pre-trip and post-trip inspections are your earliest warning system. They happen daily. They cover the vehicle’s visible condition before anyone else gets a look at it. But in a lot of fleets, that inspection data lives in a form that nobody reads until there’s already a problem.
A defect noted on a pre-trip should create a work order. Not a note on a clipboard. Not an email. A work order, in the maintenance system, is assigned to someone with a priority level.
If that connection doesn’t exist or if a driver can write “brakes feel soft” on a DVIR, and that note doesn’t automatically surface to the shop, you have a gap that your PM schedule can’t fill. A PM interval tells you when to look. The inspection tells you what the driver is already seeing between those intervals.
A PM schedule that works at one location doesn’t automatically scale across five. Every shop has its own habits, its own backlog, its own way of deciding what gets prioritized when the bay is full.
If you have vehicles moving between locations, you also have a visibility problem. Who’s responsible for the PM when the truck left Location A three weeks ago and is currently staged at Location C? If the answer is “it depends” or “I’m not sure,” that vehicle is probably getting missed.
Multi-location PM management requires two things that single-location operations can get away without:
Without both, your PM compliance numbers at the portfolio level are going to look worse than any individual shop, because vehicles that fall between locations fall through the cracks.
Getting PM intervals right matters. But the harder work is building the process around them — the triggers, the alerts, the ownership, the inspection loop, the compliance tracking. That’s what separates a PM schedule that exists from one that runs.
If you’re not sure where your current process is breaking down, look at your compliance rate. If it’s below 90%, you have a process gap, not an interval problem. The fix isn’t a better schedule, it’s closing the loop between “scheduled” and “done.”
Start there. The trucks will thank you.
Squarerigger automates PM triggers across mileage, engine hours, and calendar intervals and connects inspection findings directly to work orders so nothing gets missed between services.
See how the PM workflow works.