No Start Problems After Installing A DDEC ECM
About a third of the calls I get are from owner operators or technicians who can’t get their Series 60 started and they’re usually not in the best mood when I talk to them. It’s not a good feeling to be heading out to work on a cold morning and realize your truck doesn’t start. As of October 2017 the newest vehicle I have is a 1999 F350 powered by a 2002 7.3. Believe me when I tell you I’m familiar with that feeling on a professional and personal level.
If we’re starting up an electronic engine of any kind the first thing we need to look for is the check engine light. Not because we are looking for a diagnostic code but because we want to verify that the ECM is turning on with the ignition. DDEC controlled engines will turn on both the check engine and stop engine light for about 5 seconds and then turn them off again anytime the ignition is switched on from an off position. If no active diagnostic codes are present the lights will stay off after this sequence. When you see this happen the ECM is armed and ready to fire the fuel injectors. From here all that’s required is a valid timing signal and the ECM will attempt to start the engine.
If you see the check engine light flash, stop flashing, then flash again when you crank with the same 5 second routine this means your ignition or unswitched supply voltage is dropping too low while cranking. Batteries are the usual problem in this case. Even if your voltmeter says things are ok when your cranking your starter is spiking your truck voltage down and your DDEC is shutting off or at best not able to provide enough voltage to fire the injectors. As soon as you release the starter voltage comes back up and turns the DDEC back on. If this is happening don’t bother continuing to try to start the engine unless you’re jumping it, have it on a charger, or are about the use starting fluid.
For now let’s talk about what happens if you don’t see the check engine light come on when you cycle the key. Unless you’ve got bad bulbs no check engine light when the ignition is switched on means your DDEC is not powering up. It is very easy for the unswitched power connector to make contact with the aluminum case of the ECM while it’s unplugged. Check the fuses in the trucks battery box. Also check and see if you’re getting at least 12 volts to the unswitched power supply harness. Connect the negative probe of your meter to a clean ground. Next check the grounds though the unswitched supply harness. DDECs do not run a grounding strap so these grounds are important and vulnerable to damage. The ignition must also read appropriate voltage. Also verify the ignition reads 12 volts while in the cranking.
Next month I’ll cover a few more checks.
Written by Fernando DeMoura, Diesel Control Service LLC.
Website: www.dieselcontrolservice.com
Phone 412-327-9400