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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 36077
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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2001 F 350 SUPER DUTY DIESEL - check engine light blinks off

Customer Question

2001 F 350 SUPER DUTY DIESEL - check engine light blinks off and on now the gauges are kinda blurry
JA: Does the light stay on, or does it blink?
Customer: engine light blinks
JA: What is the model of your '01 Ford?
Customer: f350 super duty diesel 7.3
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: yes we would like to fix ourselves if possible, have tried to reset the computer
JA: Anything else you think the mechanic should know?
Customer: we have recently replaced all the injectors and installed a tuner
Submitted: 1 year ago.
Category: Ford
Expert:  Ron replied 1 year ago.

Hello and thank you for your question,

Are you able to connect your scan tool to the computer system and see what the fault code and or codes are that should be setting when the check engine light is coming on?

Customer: replied 1 year ago.
just checked with hubby and check engine now stays on codes came up as : P0603; P1316
Expert:  Ron replied 1 year ago.

Thank you for that, are you running a performance chip?

Customer: replied 1 year ago.
no we are not
Customer: replied 1 year ago.
we have just replaced all 8 injectors, wiring harnesses, glow plugs, valve cover gaskets, checked all relays, connections, electrical wiring, fuses, buses
Expert:  Ron replied 1 year ago.

Okay then you have a couple of things going on here. The code P1316 can be set due to any of the following with the under Valve Cover (UVC) Harness being the most common cause. Have him run the steps since the harness is new and see if this will help him narroe this down.

  • Shorted Fuel Injector
  • Failed Injector Driver Module (IDM)
  • Loose Under Valve Cover (UVC) Connector
  • Shorted Under Valve Cover (UVC) Harness
  • Shorted Valve Cover Gasket

    In order to determine which is failing you are going to have to have your husband do some testing for this code. See the test steps in the link below.

    If you are sure there is no performance chip on your truck then the code P0603 can be set due to any of the following,
  • Shorted 5 Volt Reference Voltage
  • Failed Alternator
  • Lost Powertrain Control Module (PCM) Ground
  • Lost Powertrain Control Module (PCM) Power

    To determine the cause you are also going to have him do the test steps in the link below.
Customer: replied 1 year ago.
thank you for your reply, our new valve gaskets/connectors are not under the cover, we have checked all of the above and no electrical issues are showing up. we even went as far as replacing the PCM itself and same code showed up. The weird thing is the truck is running better than it ever has before not using oil, no power lag, no issues whatsoever except these lights. any other suggesstions?
Expert:  Ron replied 1 year ago.

Your 7.3 should have the under cover harness and if that has not been looked into then it needs to be. These codes would not keep setting if in fact the problem is resolved. I would still run the steps I sent you to see if you can get these codes to clear.

Customer: replied 1 year ago.
we will relook at this again to see if there is anything we overlooked. I guess what I was trying to say is the new connectors on our wiring harnesses are on the outside instead of the inside, checked all for loose connections or shorts or chips pinched wires etc. When we replaced the injectors, this all came in a kit and had the new wiring connection on the outside (if I am quoting this correctly)The steps you sent refer to diagrams and attachments (for specific procedures) but those are not included. Where may I find those?
Expert:  Ron replied 1 year ago.

Give me a moment and Ill post them for you. What you needing is the engine control circuit wiring.