Diagnostic machine won't read my van

The first step to take Tom is looking for diagnostic codes stored in the vehicles on board computer. Some auto parts retailers will provide this "Code Reading" service free of charge. As your vehicle is a 1992 model your diagnostic system may be a OBD I version.
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auto parts stores
why not take it to an accredited auto electrician for the tests and have the tests done by properly qualified people

Have a diagnostic test done. This test will show which parts are defective. Testers are available at auto parts stores and some lend the tester.

you'll need a diagnostic test at your dealer

have the parts store hook up the diagnostic tool and it should tell you why that light is on. most auto parts stores offer it free of charge

More diagnostics are needed for this code. Do not replace any parts until that is done, the causes of this code are varied.

Get a diagnostics test done at auto zone or some other similar parts store. That will tell you the cause of the problem that will shut the light off when fixed.

Have you had the electronic engine control system scanned/tested for fault codes? It will need to be scanned to obtain the fault codes, this is key to finding out what the problem may be that is causing the stall. The fault code test can be done free of charge by any Autozone auto parts store, Aamco transmission or Kragen/Oriley auto parts store. Ask for a "OBD2" (on board diagnostics generation 2) fault code test.

Have you had the electronic engine control system scanned/tested for fault codes? it will need to be scanned to obtain the fault codes, this testing is key to finding out what the problem may be that is causing the engine to stall. The fault code test can be done free of charge by any Autozone auto parts store, Aamco transmission or Kragen/Oriley auto parts store. Ask for a "OBD2" (on board diagnostics generation 2) fault code test.

If you have a voltmeter, check voltage at the battery with engine running. Should be at least 14 volts. If not replace alternator. If you don't have a voltmeter, either drive to the parts store and ask them to test, or take alternator out and bring to them for testing. OK?