Sebastian RiveraAdvanced EV and vehicle network diagnostics
OEMs, fleets and shops call me when a vehicle has been down for weeks or months and nobody can find why.
Contract penalties, missed service, techs stuck on 1 vehicle, and parts replaced that were never the problem. Here's what finding the real cause fast looked like on recent jobs.
Faulty module connected
Faulty module removed<8 hrs
to find the fault
$300K
in contract penalties on the line
Everyone agreed it was a CAN problem. Nobody could say which network or why. The scope showed distortion at the end of every frame, and pulling modules 1 by 1 led to the culprit: the destination sign controller.
Network and high voltage faults your fleet or shop has already chased for weeks, and end of line vehicles that need to ship before the quarter closes. I come on site, or work with your tech remotely until it's fixed.
When your field techs or service engineers are stuck, hand me the escalation. I work it on site or live with your team remotely, the way I did for EV fleets across North America at Lion Electric, Rivian and NFI.
Hands-on CAN and oscilloscope training on your own vehicles.
Your tech stays at the vehicle. I join live on a call, and we go through the diagnosis together, test by test.
| Your team provides | I provide |
|---|---|
| A technician at the vehicle | A structured diagnostic investigation |
| Agreed equipment and vehicle access | Guidance on tests and interpretation |
| Available schematics, codes and logs | Documented findings and next steps |
How I diagnose every vehicle, on site or remote.Every step is logged in the diagnostic sheet you keep, so the fix comes with proof.
What the vehicle does, when it happens, the repair history, and the fault codes.
Which circuits, modules and networks are involved, from wiring diagrams and network data.
Voltage, resistance, current, and oscilloscope or CAN traces of the network signals.
Every reading goes into the diagnostic sheet next to the manufacturer's spec. Out of spec gets highlighted.
Connect the bad readings to how the system was engineered. This is where most diagnoses stall: knowing a system from the textbook isn't knowing how it was built to work.
On site, I make the repair. Remote, I guide your technician to it, step by step.
Re-measure after the repair, so the report shows before and after.
The diagnostic sheet you get
A real job: electric bus, intermittent cooling system faults. From my field report, with unit numbers and locations removed.
Tests performed
Mapped the cooling system and the network it talks on. Measured termination at 9 diagnostic ports, checked the network repeater, then watched the network live on the scope while the bus ran. Static checks kept passing. The live signal did not.
Expected and actual readings
Findings
A connector that was never fully seated. The locking clip was open and the connector sat at an angle, so cooling fan vibration intermittently opened 1 wire of the network.
Repair verification
The diagnostic sheet template I built is now used company-wide at a major bus manufacturer.
Got a vehicle that's been down for weeks? Send me what it's doing and what's been tried.
Discuss a vehicle issue
2
networks dropping out
1
harness at fault
Battery CAN and platform CAN were both dropping out. With the scope on both networks, I gently tugged the harnesses at E008. Every time, both networks dropped out, with CAN high and CAN low pulled down to ground. The fault was in the dash harness: replace it, clear the codes and retest.
<3 hrs
to find the fault
$100K+
in penalties already lost, at $2,500 a day
The data pointed at the pre-charge circuit in a battery pack the shop swore was new. It was a used pack of unknown condition. When the supplier opened it, the pre-charge resistor had exploded.
3 days
to find and fix it
14
technicians had already tried
14 technicians before me couldn't find the fault. The data pointed to vibration: a connector whose locking clip had never been latched. Every time the cooling fans kicked on, it shifted just enough to open 1 wire of the network.
30 min
to find the failing network
2
service centers had already tried
I was on site for training, not repairs. Over lunch, I isolated the failing network and flagged the gateway. The final finding: the wrong software had been installed on it.
The daily penalty is only the start. A vehicle that sits for weeks or months keeps getting harder, and more expensive, to bring back.
$1.1M
Median price of an electric transit bus in the US in 2024. Every spare kept to cover a bus that's down ties up that much capital.
Source: Brookings, 2025
$460
In farebox fares the average New York City bus brings in every weekday. Every day it's in the shop, that's gone.
Sources: MTA and NYC Independent Budget Office, 2025 data
Rivian
Led a 23+ person service operation. Wrote their first national recall strategy.
Revolv
Director of Fleet Engineering for commercial EV fleets.
Lion Electric
Escalation point for EV fleets across North America.
New Flyer
Tactical team, sent to buses down for months.
GM
Master certified on GM combustion and hybrid platforms.
“I like reaching out to you with our problematic buses because you are effective.”
“You're good at diagnosing these hard ones. I want to watch your process. You're really good.”
“Everyone walked away with an awesome experience, and you are certainly someone for these new to industry guys to look up to.”
Master Technician
Advanced Level Specialist
Yes. Send me what's happening and what's been tried. I personally review whether it fits my expertise, at no cost, and reply within 1 business day. Diagnostic work starts once you've agreed to the scope and price.
Yes. On site, I come to wherever the vehicle is in the US and Spain. Remote, I work with teams across the US and Europe.
Electric, hybrid and hydrogen transit buses, EVs, commercial vans and trucks. Diesel and gas too.
Yes. Your tech stays at the vehicle and we go through the diagnosis together on a live call, so by the end you have a specific roadmap for the fix, not a list of suspects.
Service packages depending on need. Remote support is hourly at 50% of your door labor rate, with a $250 minimum.
The vehicle, what it's doing, what's already been replaced or tested, electrical schematics and any fault codes or data logs with .dbc file.
Sí. I work in English and Spanish.
Text or WhatsApp
US 708-228-2954
Europe +34 645 46 27 50
Email help@canfixed.com
Got it. Thanks.
I'll personally review what you sent and reply within 1 business day. If the vehicle is costing you money every day, text or WhatsApp me too.