Codes 159, 542 and 543, engine will not stay running?

1994 FORD RANGER

176,000 MILES • 4.0L • 6 CYL • 2WD • AUTOMATIC

WAYEN1

MEMBER
1 POST

My truck will start run great for 30 to 45 seconds then stops, like the key was turned off. I got codes 159, 542 and 543. Nothing seems to help it run like it used to. The codes were KOEO test. I checked fuel pressure it’s within specs

Aug 19, 2023 at 4:50 AM

STRAILER

✓Experienced Mechanic
55,249 POSTS

It sounds like the PCM is going out but to be sure here is a guide to help check the wiring and the PCM wiring diagrams below:

https://www.2carpros.com/articles/how-to-check-wiring

Code 159: Continuous Memory Test Failed

Code 542: Fuel Pump Secondary Circuit Failure

Code 543: Fuel Pump Secondary Circuit (Lack Of) Voltage

Here is the location and how to replace the PCM in case you need it. Check out the images (below). Please let us know what happens.

Images (Click to enlarge)

Professional Diagram for 2CarPros Members
Click here to log in and view diagram.

Aug 20, 2023 at 4:37 AM