Use HDS Data List To Help Troubleshoot Problems (A11060D)

USE HDS DATA LIST TO HELP TROUBLESHOOT PROBLEMS

TECHNICAL SERVICE BULLETIN

SERVICE INFORMATION

Intermittently bad sensors, harnesses, or connectors sometimes cause driveability problems without setting a DTC. These situations are really tough to troubleshoot since you don't know where to start. Here's a handy method from Tech Line that uses the HDS Data List  to help you track down the root of the problem.

The process is to compare the sensor values of a known-good like vehicle to the one you're working on. Just make sure both vehicles are compared under the same test conditions (fully warm or fully cold).

Here's what you do:

1. Turn the ignition switch to ON (II) without  starting the engine, and hook up the MVCI and the HDS PC. Go to PGM-FI  , and then to Data List  .
2. Record the data. You can do this any way you like: snapshot, print screen, it really doesn't matter.
3. Repeat this for the other vehicle.
4. Compare the sensor values from both vehicles.
   • If any values don't  match the known-good vehicle, you need to dig further. For example, let's say the EGR value is 1.25 volts  for the known-good vehicle and 1.50 volts  for the one you're working on. That difference wouldn't be enough to set a DTC, but it could be enough to cause some driveability problems. Troubleshoot any sensors that are suspect.
   • If all the sensor values match, go to step 5.
5. With the ignition switch still turned to ON (II) and using the PGM-FI Data List  , start to gently tug and wiggle various harnesses, including the battery cables and sensor connectors. Look for any changes in the sensor values. You'll know you've struck gold when you see a significant shift in values as you tug or wiggle a particular harness or sensor connector. Once you've found the culprit, make any needed repairs, then test again to verify.

This method works just as well with systems other than PGM-FI, so keep it in mind whenever you're troubleshooting.