My truck produced a lovely indicator a few weeks ago showing a picture of what could be interpreted as an engine. In this context, this indicator is know as the ‘Check Engine Light’ or CEL.
I always joke that I popped the hood and yep, the engine was still there- checked! Of course I know that isn’t enough, but it amuses me to say that so I always do. In this case I elected to ignore the light for a bit as I had some places to go related to my own health at the time.
I did finally book my truck in for service this past week, and the problem is now resolved- and it had nothing to do with what I thought it might be.
Exhaust manifolds? Nope
I had a hypothesis regarding what might be behind the check engine light. The ‘new’ model RAM 1500s that started arriving in the late 2010’s came with a decent 5.7 litre V8 engine. Unfortunately these engines are prone to producing cracks in their OEM exhaust manifolds. I had experienced one such crack and replacement already, a $1,200 hit to the wallet.
I was prepared with a strong ‘no’ this time if the second manifold had broken. There are aftermarket manifolds that are much stronger and better made than the stock ones RAM still insists on installing, notably this one from BD Diesel.
As it turns out, however, my hypothesis was wrong: the exhaust manifold was still intact, and the problem causing the CEL originated elsewhere.
Radiator shutters and sensor network
The service guys did my basic maintenance, ran the fault code scanner, and cleared the code before running it again. Apparently this is normal practice. After clearing the code manually, restarting the truck, and taking it for a test drive no warning lights appeared: problem solved!
As it happens, however, I wasn’t able to pick up my truck on the day it was done, so they started it again to move it to their secure lot. This time it generated the check engine light code immediately: lucky me! And now they had what they needed to find the fault.
The underlying cause was failure of wiring to the radiator shutter in the engine bay. This then caused a cascade failure with the diagnostic bus on the truck, and they had to replace some additional wiring to clear all the issues. The CEL has been cleared and remains cleared a week later, so I will take that as a win.
But really, what it does for me is demonstrate why the current best practice vehicle diagnostics are a bit sketchy at best. I could have easily taken delivery of the truck and had the check engine light again the next day, causing me a whole bunch more hassle. There should be a better approach to diagnostics than “clear the error and see if it comes back- if it doesn’t it’s fixed.”
