Hi there! I have a head scratcher here. I went and got an oil change on my '05 SRT-6. Started heading home, then got a beep and oil level "HI" on the center gauge. Called the shop, they immediately took it in to see what was going on, said everything checked out but now I have a battery charge error light on. This is particularly interesting because the light was NOT on before they double checked the oil levels. Drove back home about 30 minutes and thankfully the car didn't die on me but I still have the light. Irritatingly, the oil level HI notice came back on and subsequently went away. ARGH.

So my question is that since these are seemingly unrelated issues (poor timing of coincidence?) is there anything I should double check connection wise before tearing into this and pulling the alternator and getting a new one installed? I have no problem doing it myself, it's just more of an inconvenience, if you know what I mean.

WHAT I'VE DONE:
I double checked the cables and tested the voltage at the battery terminals. Battery when I got home was low. About 12.05V and after "topping it off" and letting it sit for a couple days, it registered 12.68V and she started right up. Running the car it did dip to 12.29-12.3V at idle and then applying the throttle brought it to 12.5X Volts. So there is SOME charging that is seeming to happen definitely but not much.

WHAT I'VE NOT DONE:
I have not checked the voltage at the alternator. Seems like bit of pain to get to the wires on the back to check voltage. Any tips?

Thanks so much for your help in advance! I've had my SRT for 7 years and it's been reliable except for the RCM which was replaced with a rebuilt unit in June 2020. On an unrelated note, I also checked the oil levels and things seem to check out. Any chance the low voltage from alternator is making other things go crazy?

 

The HI iol light is probably because they put a little too much oil in and when it gets hot, expands, it triggers the warning. If it is a bit high going uphill can also trigger it. Will it hurt anything? Probably not but it may be a bit irritating. As for why the charging light, I would look to see if they got oil in the alternator. Who changed you oil, a quick lube?

 

I'll take a look. The shop was an A1 Auto Service in Everett, WA. Nice people and all but this is a bit annoying of a first impression.

 

I hope they used proper 0W40 synthetic oil and a fleece filter.

 

A quick/easy alternator test: with car running use your volt meter across the battery terminals on the AC setting. You should not get any voltage. Something like .02 is okay it will bounce around a little but nothing much more. If you do show AC voltage your alternator is bad.

 

Thanks all for the tips! It was indeed the alternator. Got that ordered and swapped and I am in business.

Curiously, a P0500 code came yesterday for the "Vehicle Speed Sensor A Circuit" along with the return of the BAS/ESP and ABS light. No cruise control. Research on this seems to point to wheel speed sensors. Sadly no shops near me can diagnose for over a week. 😬

 

Waste of money. If you take it most anywhere, you will spend a LOT of money for them to GUESS.
SO.......
Just slow down. Wait till you get the new alternator on. If the BAS/ESP light wont go out, replace the battery.

THEN and ONLY THEN should you start throwing money at the BAS/ESP light. You have an electrical disturbance in the car, the alternator was undercharging - dont go all half-cocked after a problem until you resolve the FUNDAMENTAL issue.

 

Thank you for the tip! Sorry if I wasn't clear. The alternator has been on since Wednesday, then the P0500 came after the alternator was replaced.

I was able to drive the car for hours without issue but yeah, even with the alternator (which fixed the charge system light), BAS/ESP, ABS, and Check Engine currently are on.

I have a Mercedes code scanner from Amazon coming tomorrow to scan it and see if it's got anything more specific.

The battery was replaced 3 years ago but did sulfate during the pandemic. I can also check that.

Appreciate it!

 

The only way to check your battery is to have it load tested.

 

A battery voltage should increase about 1 volt from off-resting to running 12.5-6 to about 13.3-5 or so. Battery voltmeter for cigarette socket is my recommendation, walmart like 18$. Monitor while driving...

High oil is nothing to concern about, I always run about 1/2 to 3/4 " above full mark for the high speed corners and such, since I push it. I use full synthetic 10w40, oil film is your friend. My 440 6 pac challenger (1973) has 20w50 oil at 7 quarts and it never gets started without oil pressure! I made a pressure tank in the trunk with additional 2 quarts of oil under pressure, opened before I crank it over, with 20# on the gauge. When engine is running oil gets pushed back to tank and is valved off for next time.

Enjoy Woody, check my albums for more..

 

Interesting option for an electric oil pump (a friend many many years ago had a P/U jacked high (among a whole lot of other mods), he modified the oil filter assembly on the block for dual oil filters and an electric oil pump. Every time he got in, he 'pre-charged' the oil system before starting. This guy was a fanatic about dry oil passages starting.


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Battery replaced today and I used a Launch diagnostic scanner to wipe the codes and go for a drive. All lights and errors returned after three drive cycles. Same codes as before. This is from the diagnostic report.

1. Traction System RL Wheel RPM Error2. "Rough Road Detection" Signal (by comparing Wheel Speeds) Speed Signal From Control Module ESP Implausible / Read Out Fault Memory of Control Unit ESP (P1999)
3. No CAN Message 'Vehicle Speed Signal Left Rear Wheel' From Control Module N47-5 (ESP Control Unit) or Message Faulty. Read Out Fault Memory of Control Unit ESP (P0500)
4. The Left Rear Wheel RPM Signal Sent From The Traction System Via The CAM Bus Is Implausible

Also
1. B24/2 (ESP Lateral Acceleration Sensor)

Link to report: Inspection Report
Thanks again for all of the guidance! So far I have a wheel speed sensor coming ($19) and have located the part number for the lateral acceleration sensor to be Mercedes # a1635420618 which appears to be different than the YAW sensor some people have to replace. I'm planning to open the center console to get my eyes on the sensor before ordering it on eBay ($45-80 for a pre-owned). I suppose I can call the local Mercedes dealer in the AM and see if they have the sensor.

Cheers!

 

Forgot to reply! It totally failed a load test. Was only putting out 400 or so CA instead of 730+ (Battery was rated for 730 cold, 900 regular cranking amps.)

SOH was 58%

I was able to get a prorated replacement (8/22 manufacturing date on the new one!)

 

I would not open the console or replace the yaw sensor yet. These cars can have strange things crop up when a speed sensor goes. It doesn't hurt to read the service manual and posts about the medium to hard console removal/install but you just might not have to need a yaw sensor. Please remember the OBD codes are only an indication of what system flagged, it could be various different other things (like maybe a defective speed sensor) that is also causing the yaw sensor OBD code popping up. If replacing the speed sensor clears up even one OBD code, you have saved a bundle of $ in your DIY. Good luck!


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Thanks for letting us know.