Rick's Free Auto Repair Advice

What is a PCM/ECM FLASH update?

Understanding a PCM/ECM FLASH update

Car makers issue a FLASH update when they discover a software bug that can set a false trouble code or cause performance issues. Once they’re aware of the problem, they re-write the software to correct the mistake. Then they issue a service bulletin to dealers and independent shops informing them of the availability of new software that fixes the problem.

Referring to the service bulletins BEFORE performing diagnostic work can save the shop a lot of wasted effort. It avoids replacing perfectly good parts that don’t actually fix the problem. If a customer shows up with a symptom that matches the service bulletin’s description of the problem, the shop should always make sure the vehicle model and build date matches the vehicles affected section of the bulletin. If it does, the shop should perform the flash update first before performing any diagnostic work.

How is a FLASH update performed?

To perform a FLASH update, the shop must own a J2534 Vehicle

pass thru VCI

OTC J2534 Pass Thru VCI

Communication Interface (VCI). The VCI connects to a laptop PC computer on one end and the OBDII diagnostic link connector (DLC) under the dash. Prior to performing the upgrade, the shop visits the car maker’s site and enters the VIN number for your vehicle. The site pulls up all the available software updates.

The shop choses the update mentioned in the service bulletin and downloads it to their PC. Then then connect the PC and VCI to your vehicle. The vehicle computer must have battery power during the entire FLASH update, so the shop will connect a battery charger and set it to a low charging rate.

Then they activate the update. Flash updates can take as little as 5 minutes to complete or as long as 45 mins for a large re-program.

How much does a FLASH update cost?

Independent shops must pay for access to the car maker’s technical site. They can buy daily, monthly or yearly access or the shop can buy software updates for just a single vehicle. For example, GM charges a flat $40 to access all the software/programming for a single VIN number.

By the time the shop download the update, hooks everything up and waits for the update to complete, you’re looking at one hour of shop time plus the cost of the update. Depending on the labor rates in your area, that’ll cost between $150 and $200.

Can you do FLASH reprogramming yourself?

Well, yeah if you are willing to invest in a J2534 interface. You can buy universal J2534 VCI products that work will all car brands or you can buy a VCI just for one car brand. A universal VCI runs around $1,200 while a make-specific unit runs around $500. However, you can find some used ones on ebay for less than $300. Here are choices from Drew Technologies

Mongoose VCI

Mongoose VCI

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Posted on by Rick Muscoplat

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