OBD-Sniffing A Caddy PHEV

The Cadillac ELR is a plug-in hybrid car with a bit of class, it has the beating heart of a Chevy Volt in a nice coupé body with some up-market styling and a nice interior. Since it wasn’t on the market for long and some consumers are still wary of cars with electric motors, it also represents something of a sweet spot: according to [Andrew Rossignol] you can pick them up for less outlay than you might imagine. He bought one, and being an inquisitive soul decided to probe its secrets through its OBD-II ports.

OBD-II sniffing is nothing especially new, but his write-up provides an interesting run-down of the methodology used to identify the different proprietary pieces of data that it makes available. His Python script attempted to parse the stream as though it were multi-byte words of different lengths, plotting its results as graphs, It was then a straightforward process of identifying the graphs by eye that contained useful data and rejecting those that were obviously garbage. He was able to pick out the figures in which he was interested, and write an interface for his little Sony VAIO UX to display them on the move.

We’ve covered OBD hacks too numerous to mention over the years, but perhaps you’d like to read our history of the standard.

25 thoughts on “OBD-Sniffing A Caddy PHEV

  1. Didn’t realize these were off the market already. Seems like Cadillac has a tendency to put out really cool vehicles, but only keep them on the market for a few years. Like the XLR or the Allante.

    1. In this case it was a product without a market due to being way overpriced. It was just a polished Chevy Volt with an $80k price tag. If they had added more torque or a bigger battery that would have helped but adding $40k to basically the same car was a non-starter.

      1. NOT True at all Thats like saying a Camaro is a Corvette because they have the same Engine. THe Volt platform UNDER the ELR is the same. But thats where it stops. The suspension, brakes, interior and exterior are all different. The REAL reason wasnt JUST cost, it was competition IN the Cadillac Showroom. When it was released.The ATS Coupe was just released and the last year for the CTS-V also, all three look similar. The ELR was about the same cost. ADD to that, only 25% of the dealers even took stock of the car. 65% of the dealers opted out of training their service departments on the car, and thus GM woudnt sell them the car. It comes down to as much timing and poor management decisions at GM as it does cost.

      1. Well, it’s a Cadillac. Nobody is buying them because they are cheap, they are luxury vehicles. Comparing it to a entry-level hybrid isn’t really valid.

        Price wise it looks like it was about on par with the Tesla Model S. Though of course that’s comparing an ell-electric with a hybrid so even there it’s a bit sketchy. But at least you could argue they were targeting roughly the same demographic.

        1. If it’s truly a luxury vehicle and not a reincarnation of the Cimmaron, the price point might be ok. Adding luxury features to a cheap car rarely ends up as nice as designing a car from the beginning for ride quality, etc.

        2. I have a 2012 Volt myself. In quite a lot of ways, it IS a luxury vehicle, albeit a fairly sporty one – Not cushy and squishy like a Buick I once owned, but to me it’s luxury in that it’s quiet, reliable, comfortable, quick enough to not be last in line, good stereo etc etc. Handling is awesome – I have fun blowing off those who assume it’s a golf cart on the twisties where I live. Plenty of haulage due to the hatch and folding seats. The Cadillacs don’t have much on them – certainly not double the price worth.

  2. On his blog, he mentioned the car has a range of 35 miles (but he managed to get 44 miles).
    As it is a hybrid, is he able to drive it in a “battery only” mode, or it just ran that far before the Internal Combustion kicked in?

    Is there a second DLC under the passenger side dashboard? That one photo shows a cable going there.
    Is that brown stuff _rust_ pictured around the main DLC?

    1. The rated average range is 35 on that pack, but that will vary on driving, terrain and weather conditions.

      It is a hybrid, but the Voltec platform is ordinarily all-electric drive, even when the internal combustion engine is running. Under normal operating conditions, motive power is provided exclusively from one of two electric motors.
      To answer your question, yes. It runs in battery-only mode until the state of charge drops below a set value, at which point the ICE starts to generate electricity for the traction motors.

      There is one condition, at lower speed, where the engine *can* directly turn the wheels, but my understanding is that it’s locked at 1:1 or something around there, so it isn’t used often.

      1. I own the equivalent Volt. At speeds (approximately) 30-60 mph, if the engine is already running (like say in mountain mode, or you’ve run the battery mostly down) and you floor it, it’s the one time you can feel it “shift” and it’s really a kick in the pants, as for a little while, you have all the horsepower of both electric motors plus the engine (85 hp more then usual). The transmission is a planetary with 2 input shafts, and the engine shares one with one of the electric motors. Normally the CVT effect is due to variations of the two motors rpms on those shafts, or a shaft can be clutched to “ground” or stationary. All done with perfect rev matching and you don’t feel it normally, but the gas engine, you can feel it, as motor #2 has to rev match the engine before the pair are clutched together and then back in, so for an instant during the shift it’s just one electric motor instead of the usual two.

      1. Owner of said caddy here: it’s definitely not a flood car, it was about $1000-$2000 less than the going market rate because it has slightly more mileage (though still under warranty, which is nice). I looked at by the track record for Volt reliability and took a gamble assuming that the Cadillac will be just as reliable (aka, very few issues with the drivetrain).

        I thought this steel color was odd too. I believe it is some surface oxidization (rust sure, but pretty mild) of the exposed steel. That or it’s some other kind of surface treatment. Either way, it’s not uncommon to see something like this in parts of the interior that you don’t see. I remember my first car, a Dodge Neon, had a couple of spots like this if you removed the dash pad.

  3. Hmm it doesn’t appear he’s tapped into GM-LAN which is a single ended CAN bus where most of the interesting bits of data are sent. It’s also the bus with the most reverse engineering done by the community at this point.

  4. The Volt is one of the best handling cars I have ever owned. Bought a 2014 for my wife’s birthday and she won’t let anyone else drive it. In sport mode we call it “Tesla” mode because it pins you back in the seat.

    1. If you have an opportunity to try a real Tesla, you’ll be shocked at feeling of being pinned. The ELR has the same exhilaration, and that comes from the simple single-speed EV gearing.

      What I love about this ELR is the sport mode that tightens up the suspension. It corners really well compared to my Tesla (which is over 5000 pounds, about 1000 pounds heavier than the ELR). Despite what you may read (aka lots of haters), there are some good merits to the ELR (especially given what they are trading for on the used market now).

    2. What I found most impressive in my Volt was the cornering and stopping. (there’s a youtube video of mine called VoltSlide where I take a 15 mph rated hairpin at a tad over 60 – and drift 3-4 inches off my line…not shabby). It was very competitive with my 2010 Camaro SS, giving up only around .01 g on the skidpad…Almost unbelievable but then there’s that near-zero ground clearance in the Volt.

      Yeah, if you’re first at a light and it’s multilane, if you’re not careful you’ll always jump 50 yards ahead of everyone else, but for sheer, power, it’s a nope at high speed. Fine with me, where I live it’s all twisty roads – I have to drive around 9 miles to get to a half mile straightaway.

      In general, the transient response of a Volt leaves little if anything to be desired. It’s not a Tesla, but I wish someone around here would get one to race me with on the twisties where it’d probably be a pretty even contest.

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