Hello,

I have a '14 V8S with 55k miles. A week ago I got the array of messages: "Emergency Brake Assist not available, Stability Control not available, drive with caution, e-diff not available" and so on. I suspected the battery since it was the original. I replaced it with a fully charged (13.6 v upon installation) battery. I can erase the codes but they come back after about 15 minutes of normal driving. Since replacing the battery I've put about 100 or so miles on the car so it's had plenty of time to drive cycle.

Any thoughts as to what it could be? Wheel sensor?

I took it to an empty parking lot and confirmed that all the safety features are indeed off so the messages are real.

thanks

pat

 

I think you'll need to see what codes are stored, and be aware of the battery reset issue after connecting an OBDC reader.

 

It could be the connection to the battery. Several members have found corroded leads/grounds to the battery and it can cause voltage issues which act like a bad battery. Make sure they are all clean and tight (and not just the leads on the battery itself, but any major grounding point connections or power distro point connections).

 

Thanks Matt, I'll double check the battery connections but I didn't notice anything out of the ordinary when I replaced it last week.

I'll get the car up in the air when I get home tonight and see if there are any obvious issues with the acclerometers, sensors, etc and report back.

pat

 

I'd check for codes before any of that. All those features unavailable means the system detected faults, so why not ask it what they were?

 

Although a bad battery or battery connection could indeed produce warnings such as these, the poster says that he checked in a car park and found that the messages were correct. It would seem therefore that the fault must lie elsewhere - I'm not knowledgeable enough to suggest where though!

 

Hi Steve,

Yeah, I checked both. I guess I'm more of get your hands dirty first kind of person but your point is well taken. The code is P2159 Vehicle Speed Sensor B. According to my workshop manual it could be AB control module but also a problem from the e-diff motor could be at issue. At least I seem to have narrowed it down somewhat. All the connectors looks fine but I start checking voltages and fuses to the individual components. It might be a few days before I can really look into it.

Thanks for all the suggestions.

pat

 

I'll second the suggestions that you check/verify the battery connections and the caveat about OBDC disconnects/reset, and add that you should put the new battery on a CTEK for a good, full run. A new battery does not equate to a fully charged battery, so the same gremlins could persist. Certainly, on a MY14, you were past due for a battery, so you haven't wasted anything so far.

 

Yes, checked all that and had the new battery on a CTEK charger prior to installation. It's definitely not a problem with the battery or the connections.

thanks
pat

 

Does the V8S model have the Aux battery? The 2014 MY V6S did which is why I ask.

Mine had all sorts of weird electrical gremlins until I pulled the negative wire off the 2nd battery. I am planning on replacing it, but right now I am enjoying not having to press the ECO button.

 

Yes, it does although it looks nothing like all the pictures from people DIY'ing the removal of the aux battery from the coupe. It's long been dead so even though the 'eco' light comes on, stop/start hasn't worked in years. I might try what you did but since it has not worked in so long I'm not sure if it will fix the problem, easy enough to try though.

pat

 

Mine was dead as well, but from what I have managed to put together it killed the battery a previous owner put in the car in 2020 & I was taking no chances when I replaced it with a new one.

 

I understand. I was a Saab mechanic during the transition to electronics and remember when the factory service manual started saying "check these things, and if correct, swap the ECU with a known good one. If the problem goes away, it's the ECU."

I'm envious of the lift, as I no longer have access to one. Oh, what fun I'd have ...

Good luck!

 

Well, I stand partially corrected. The problem was the battery, just not the main battery. I disconnected the ground from the long dead Aux battery and the problems went away as GeaBaldyVx suggested. 200+ miles since disconnecting the aux battery and all is well.

Thanks everyone for the suggestions. I'd love to hear an explanation if anyone has an idea why this would cause the problem. I'm stumped.

 

Woohoo a win for the new guy.. lol

The only thing I could figure is the gateway module is trying to do it’s job and keep the Aux battery charged, but in doing so it doesn’t understand that the Aux battery isn’t outputting the proper amount of power in the loop. You would think that perhaps the Jag programmers would have maybe put a warning light and sent the gateway module a code to stop trying to charge the Aux when the output didn’t meet a spec, but I have a gut feeling some of those guys started out working for Lucas and slipped thru the Ford years into Tata undetected.

 

I think a lot of people are driving around with dead start/stop batteries with no issues. I finally removed mine after it was dead for a few years.

 

Yeah my new-to-me 2015 had the second battery, but even though the ECO light did come on, it never did the start/stop. To remove its potential contribution to crazy warnings, it was removed with no side effects.

 

When you guys removed your auxillary battery what did you do with the cables.

 

IIRC the negative cable comes away with the battery (providing you unbolt the earth/ground connection) and I just left the positive cable in the car but zip tied up so it can't contact any metal part.

 

I removed all of it, battery, cables, junction connector. It'll live in a box and go to the next owner.