If your head hurts just looking at that mazelike thing, keep reading. Sonnax has a tool that’ll help decipher it. (Image/Summit Racing)

Ever look at an automatic transmission valve body? It’s a complex network of passages and valves—we’re talking “Rube Goldberg meets M.C. Escher” level complexity here.

That means diagnosing automatic transmission problems can be really difficult. From weird, loud noises to erratic shifts, there are a ton of issues related to automatic transmission valve body problems.

That’s why the Sonnax Transmission Company comes to the rescue with its Vacuum Test Plate Kits.

At the heart of each kit is a clear test plate that fits over the entire transmission valve body casting, sealing all of the critical passages. The test plate has strategically-placed ports where you can check vacuum in isolated passages—helping you quickly determine where the problem areas are.

Better still, Sonnax offers a ton of free vacuum test data reference guides on its website for most common automatic transmission models, complete with specific problem diagnosis and replacement part numbers. Check out this one for the GM 4L60-E:

This is just a small section of the comprehensive GM 4l60-E troubleshooting guide that Sonnax makes available for free on its website. Combined with its test plate kits, your automatic transmission repairs may have just gotten a lot easier. (Image/Sonnax)

If you want to see how helpful vacuum testing can be in troubleshooting an automatic transmission, Sonnax even created a video that’ll walk you through the process. Check it out here.