Piston Slap: CAN Busing Around a No-Start Van?

Sajeev Mehta
by Sajeev Mehta
Bob writes:

Hello Sajeev,

My wife’s 2012 Grand Caravan has a quirk: an intermittent no start condition when the key is inserted into the ignition and turned. Dash lights come on, but engine doesn’t crank. Doesn’t seem to matter if I cover the brake or not. Doesn’t seem to matter if the row the gear selector a couple times. After 3 or 4 attempts of turning the key it suddenly starts and drives.

I researched fuse boxes, but the symptoms don’t quite match. I researched the neutral switch device, but once again symptoms don’t quite match. Ignition switch might be the culprit? My red herrings:

  1. The car has stalled, intermittently, a half-dozen times while driving to work at roughly 35 mph. Pull over, and it restarts.
  2. My best friend’s wife has a 2013 Town & Country with the same problem. We were both shocked.
  3. When we first bought the car, we lost the one and only original key. So not wanting to pay the dealership fee of $500+, the internet found a guy who could do it from the back of his car for $200. The keys are Dodge keys, but not Grand Caravan specific. They have worked fine, but I wonder if once in a blue moon the ignition switch decides it doesn’t like the impostor keys? And my friend, who has the same problem, has their original keys?

The van has been a godsend for our three kids and dogs, so the idea of going to a SUV or Mega-truck sounds like a lot of money for less space, but I can’t have her driving around wondering if she will stall in traffic, or — more annoying — just can’t start after loading up to go somewhere with the kids. The dealership is useless unless they can replicate it. And it never does it when you want to show someone.

Perhaps the car is possessed by the ghost of passenger from its prior rental life?

Sajeev answers:

I love these questions because, if I get it right, we both learn something new. After bricking my (seemingly) rudimentary Ford Ranger when the gauges mysteriously failed died from owner stupidity, I realized the level of connectivity in modern vehicles. Behold the CAN bus system: even more than before, throwing parts at problems is beyond stupid.

Instead, pay for an expert diagnosis, but read this article by Brandon Steckler first. Remember the recalls on related modules in this body style’s recent past: we also discussed the Totally Integrated Power Module (TIPM) previously — I reckon it’s the problem behind this intermittent no start condition.

Or it is the power/ignition/ground wires to the TIPM.

Or maybe both: how you gonna know, son?

You find a zen-master level technician, paying handsomely for a complete diagnosis: there’s a highly-educated, local automotive mastermind at an independent shop, or an FCA dealership nearby that’ll be up to it. Reassure them you are willing to pay for a diagnosis that unequivocally gives a clean bill of health to the TIPM, WIM, ECU and (maybe) the entire CAN bus.

The work is pricey (hourly rates for skilled techs is brutal for good reason) but the alternative is spending hundreds on a new TIPM while mindlessly hoping it’ll do the trick.

[Image: Fiat Chrysler]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.


Sajeev Mehta
Sajeev Mehta

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4 of 36 comments
  • DenverMike DenverMike on Nov 02, 2018

    Once you're down to just one key, use it to bypass the transponder system and use (unlimited number of) "dummy keys" from then on. My '04 F-150 required me to have a factory transponder key within 4 inches from the ignition for the dummy keys to work, but a couple years later, it required it within 2 inches, but now requires the transponder key basically touching the reader. It might eventually have a problem reading the transponder key in the actually ignition.

  • Grenade Grenade on Nov 02, 2018

    You need some specialized equipment, and a seasoned troubleshooter to find CANBUS issues in a Dodge. Here's a youtube video from South Main Auto Channel where he diagnoses an FCA van with an intermittent issue with the wipers coming on when the power sliding door is opened. https://youtu.be/Q0gTP2zerV4

    • See 1 previous
    • Scoutdude Scoutdude on Nov 02, 2018

      And a lot of luck. That problem could have literally been anywhere along that bus. I did want to yell at the screen a couple of times, "pull up that carpet" and "CAN L short to ground" I'm both surprised (because it would be easy to implement)and not surprised (because Chrysler) that there wasn't a code somewhere that was CAN to ground or CAN L to ground.

  • IBx1 Never got the appeal of these; it looks like there was a Soviet mandate to create a car with two doors and a roof that could be configured in different ways.
  • CAMeyer Considering how many voters will be voting for Trump because they remember that gas prices were low in 2020–never mind the pandemic—this seems like a wise move.
  • The Oracle Been out on the boat on Lake James (NC) and cooking up some hella good food here with friends at the lake place.
  • ToolGuy Also on to-do list: Read the latest Steve S. fiction work on TTAC (May 20 Junkyard Find)
  • 1995 SC I'm likely in the minority, but I really liked the last Eldorado best. That and the STS.
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