1990 Ford Bronco II 4WD, Standard, M5OD-R1FACTORY OEM SERVICE PROCEDURE

Step 5.0 Perform Engine Running (KOER) Self-Test: Introduction

The Engine Running test checks for hard failures with the sensors under actual operating conditions and at normal operating temperatures. The actuators are exercised and checked for expected results.

An "Engine ID" code is issued at the beginning of the Engine Running (KOER) test to verify the proper processor is installed and that the Engine Running test has been entered. The engine ID code is a one-digit number represented by the number of pulses sent out.

For gasoline engines, the engine ID code is equal to one-half the number of engine cylinders (i.e. 2 pulses, = 4 cylinders). For the 7.3L Diesel engine, the ID code = 5. Be aware that a response is required for some vehicles after the engine ID code. Details are below in the test.

After the Engine ID code, a "Dynamic Response" code may be displayed, which is a request from the ECA to perform a brief Wide-Open Throttle (WOT). The WOT allows the ECA to verify the movement of the TP, VAF, MAF and MAP sensors (as equipped). False codes will result if not performed. The signal for the operator to perform the brief WOT is a single pulse or 10 code on the STAR Tester.

Now the fault code(s) or a pass 11 are displayed. Like On-Demand codes, they are never stored or retrieved from memory but are created only when a hard failure is observed during the check. Intermittents may be overlooked.

Note that any hard codes displayed during the Engine Running test are not referred to as On-Demand codes, but as "Engine Running" codes. Ford actually distinguishes between the two "categories" of hard codes; the On-Demand codes taken when the engine was off, and the Engine Running codes taken when the engine was running.

Lastly, be aware that neither Separator nor Continuous codes are shown in the Engine Running test. Also, Fast Codes are output during this test. They are sent after the WOT request in the KOER test. The same details about Fast Codes found in the Introduction of STEP 3.0 are applicable.

Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.