Blinking preheat light 6BTA

[Charles Burton]

I have a 2002 Bayliner 3988 with Cummins 330s. When I am running fast around 2400 RPM and above for extended periods like 30 minutes my STBD preheat light blinks at a constant rate of about once every second. If I slow down, it continues to blink but If I stop and restart the engine there is no blinking until I run at high RPM for extended time again. All other temps are normal. Wide open throttle is about 2900 RPM and even at that speed all temps are normal.

I can not find any explanation for a blinking preheat light indication in either the Bayliner or Cummins manuals nor can I see any circuit in either Bayliner or Cummins schematics that would generate a constant rate blinking preheat light. But the functions of the Electronic Heater Control Module (ECM) are a mystery to me.

What does a blinking preheat light indicate? Is this indication resulting from the air temperature sensor on the aftercooler saying the induction temperature is too high? Is the ECM blinking the light? If so, at what temperature does the sensor/ECM decide the air is too hot?

Topic

[Rob Schepis]

The air heaters are controlled by the ECM based on time, rpms, IMT and low voltage. Bayliner did their own thing when it came to setting up the helm gauges, alarms, etc. With a twin setup you have the option of comparing how things operate and swapping components for troubleshooting. Have you been on the Bayliners forum? A good place for Bayliner-specific things..

[Charles Burton]

When I bought the boat I found that the aftercooler cores were aluminum and I was unable to get the cores out. I bought new aftercoolers from Seaboard 1 year ago, now about 100 hours on them.

I usually try to understand my equipment but just can’t find anything describing the ECM functions. But if it is a non problem I will try to ignore the blinking.
Thanks

[Tony Athens]

No real way to troubleshoot the system .. Certainly nothing to worry about, but if indeed the IMT is getting hot enough to trigger the themosister, and you really wanted to see if that is the case, then remove the aftercooler from the engine and service/ clean it per my protocol.. Maybe it’s a warning that I have never seen..And maybe your aftercoolers are overdue for servicing anyway……..Last time it was done was ?????????

Tony

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