Hi all, my newly acquired 2007 SRT Coupe has thrown up an engine warning light about 3 hours into a 6 hour trip. Initially this was followed during the drive with an intermittent BAS/ ESP warning. The car de-powered itself, but otherwise drives fine and no other issues.The engine light is on, but the BAS/ESP has not returned during subsequent short drives.

The original owner had been in touch when I was buying it to say a smaller pulley was added to the supercharger and the car was tuned to increase HP.

My experienced long-time mechanic, who has owned a Mercedes SLK previously, read the 9 error codes (all were labelled "Stored" btw). They wouldn't clear. Before he starts working backwards through them to eliminate each sensor or mechanical issue, I thought I would check if anyone recognises the first errors in the sequence - which may be causing the rest.

Two errors in the SLA were cleared: 1 ) CAN Bus circuit faulty and 2) reverse lamp supply circuit open

ESP errors
1 - PCM Coding Incorrect
2 - CAN malfunction PCM Timeout
3 - CAB system undervoltage
4 - Steering angle sensor malfunction
5-9 are steering angle related + ESP torque interface locked.

The mechanic wondered if the PCM coding message arises from the tuning once done to the car.

Do any of these sound familiar to forum members?

 

I have some thoughts:

Items 3-9 sound a lot like system-voltage-induced errors that are common with our cars. BUT, generally, this will not cause drivability issues.
Unstable system voltage does cause a LOT of weird errors related to the BAS/ESC system. For these symptoms:

Replace the battery today.
Made damn sure the battery cable clamps are clean and tight. If you suspect the internal part of the battery clamp(s) are corroded, change the cables.
Put in James' redundant ground mod, DO NOT do my mod, do HIS. https://www.crossfireforum.org/forum...le-engine.html

Other than that, I'd be talking to the person who did the tune about those other items.

 

Thank you Pizzaguy. I had the battery checked first thing and it passed. Wouldn't that be sufficient? I will check the cable clamps, though I would have expected my mechanic to spot that. The ground mod is new to me so will check.

I don't know who did the tune, but we have our country's best tuner only a few kms from me, so I could take to them to assess?

Mb

 

Hi
The "PCM Coding Incorrect" may be related to the engine tune. If the wrong flash file version was loaded it may not be fully compatible with the existing SCN coding in the ECU. This would generate that error. Ask your mechanic friend to check the file version loaded in the ecu and report back. I can look it up to see if it's correct or not.

 

Thinking about it a bit more..... That error is probably OK! If the the ECU has been tuned and the SCN coding has also been changed from the standard coding (eg. EGR, Air Pump, Rear 02 OFF) then the new non-standard coding can also generate this error. However, that type of error won't cause an engine light.

One other possibility is that the fuel trims are adapting to the new tune and this has temporarily generated the light. If the light doesn't come on again then everything is OK! If it stays on then look at the long term fuel trims to see if they're within limits.

 

The tests that "mechanics" do on the battery is a draw test. Over the 15 years I've been on here, it has become obvious: The battery can pass a draw test and yet, not do it's filtering job well enough.

Batteries have a capacitive reactance characteristic that fades with age, but not at the same rate that their current sourcing capacity fades. In cases of weird issuse like: BAS/ESP errors, powered wing acting "funny" or a power top that acts up from time to time, a new battery often cures the problem - even tho the battery "tests fine at the shop".

But I also think CL770's advice is probably as valuable as any I can offer. Go ahead, pursue the tune issues as he instructs - but just keep in mind what I've said about the battery. Let's see where this goes.

 

Thanks CL770. The tune is not new. It will have been done over 10 years ago. But I take your point that the tune probably isn't responsible for the engine light. That will mean the mechanic will need to start from the last error code in the file (#NO steering angle message) and gradually eliminate each.

According to the diagnostic report from the mechanic, the vehicle software version is V10.48. Is that the ECU version?

I'm wondering about taking it into a tune shop for them to assess it for me. It would pay to understand, and have a record, exactly what has been modified. What do you think?

 

Thanks Pizzaguy. I owned a Chrysler Voyager for 20 years, so got firsthand experience of darn battery weirdness - and I went through many batteries. Probably an average lifespan of 2.5 years each.

I've subsequently discovered this battery in the Crossfire is just over a year old. It does seem unlikely to be a battery, but I'm sorely tempted to buy a new one. I can always keep the current one as a spare.

 

battery dying can cause coding errors.

 

I had a early 2000's Dodge Durango that left me stranded, engine would crank over and over, try to almost start, then die. Got towed, guys worked an hour on it.
Then they traded the battery between my van and Durango - the Durango started right up as did the van - swapped batteries back, Durango no start but van still started.

You cannot say, "I had the battery tested", it's just meaningless these days.

You would certainly know about that, first hand.

 

Update for those interested.

My mechanic has gone over the car with a fine tooth comb and all sensors and mechanicals are working as they should.

After a reset or OBD clearance, all the error reports return (but without specific codes), the engine light returns and the car goes into a limp-home mode that is very drivable - just sluggish.

Not sure if this is relevant, but mechanic noted that in live reading O2 sensors on right were steady, but sensor on left gave wildly erratic readings. Swapped sensors, and left still played up. Tried sensors on another mercedes and they were fine.

The mechanic thinks the problem is a compromised ECU. Local tuner and Australian tuner concur based on the reported action, but local tuner won't touch it in case of bricking the unit without the original file to flash to the ECU.

The car was tuned by the local Mercedes dealer probably 2010-ish, before I owned it. I will check with the dealer, but it has since changed hands.

So what do I do?

I think my only option is to talk to Needs Wings about an ECU replacement?

 

You can either talk to Needswings, contact info is on the bottom of the page:
https://www.needswings.com/crossfire-limited-base-04-08

Or the Mercedes Swap Shop, their contact info is also at the bottom of the page:
https://themercedesswapshop.com/

By the way, Ganny X, who offered a suggestion above is from the Mercedes Swap shop.
They are all good knowledgeable people.

 

Thanks M60A3Driver

Small update. I've managed to talk today to the original owner (NZ is a small country!), who worked for the Chrysler franchise in NZ. It was his work car. He bought it back a few years later and did the tune himself through Eurocharge. He may have the original file (or Eurocharge might?).

Bonus: he has kept track of the car through its life so have given me its full history - which also explains its extraordinarily good condition.

 

Hi

I don't like the sound of a Mercedes dealer having done the tune, the current tunes are much better then the ones we had 10yrs ago. I can check out your ECU for you no problem (and repair/replace if necessary), but you'd have to send it to me here in Brisbane. I do ECU and TCU repairs/tuning and sell my TCU tunes through the Mercedes Swap Shop in the USA. I'd suggest a new ECU tune and a matching 4 mode TCU tune. You could also give me a call if you want to discuss some of the DTCs and I can steer you in the right direction. However, the first things you MUST do (as suggested by others) on a Crossfire is to ensure you have a good battery and a good RCM module. Send me a PM and I'll send you my contact details.

 

That's great that you were able to get all of that information!

 

Hi all,

The end to my engine light and PCM coding error was all too predictable: An RCM with dry solders.

An auto electrician using a mercedes code reader detected live errors in O2 and Supercharger ground, but traced them back to the RCM. Resolder the joints and everything cleared.

The PCM coding error was a stored error, not live, and not relevant to this problem.

Thanks you all for your comments, and to those who insisted I check the RCM!!!

Although the joints are probably now good, the relays might not - so I plan to buy a backup RCM to carry in the car.

 

I helped a Graeme Quensell with this same issue 2 years ago. He's from NZ. By chance did you get the car from him?
Just wondering.

 

Was his an SRT? No, I didn't get it from Graeme, but an Andrew in Rotorua.

The auto electrician said it looked like the RCM had been checked out in the past - probably not surprising - but only because someone had added of silicon.

Now the car is running fine, but the alarm sets off a minute after remote locking. Would that be related to the RCM resolder?