Now What.. Lit up like an Xmas tree
 

Today while driving I had all the warning lights come ABS, BRAKE PAD, etc, along with a host of messages on the MFD, Check Antilock, ETC Electronic Traction Control, CHeck Brake Pads. At the same time the speedometer and went to 0, the tach still worked. It didnt go into limp mode drove fine. About a mile later lights went out and havent come back on. I have had this happen after a bunch of stop and go trips when I start the car, the warning lights stay on, and it will be in limp mode. Sometimes it would go away and other times I would have to shut her down and restart (with fingers crossed). My first thought is battery voltage, but when it does it when I start the car, I immediately put the ACC into diag mode and toggle to number 24 which is battery voltage and it shows from 12.5-13.1v

I also get the P0600 on OBD, serial connection failure which itself has a whole host of possibilities

Any thoughts, might just have a bad battery. When I bought Dec 05, it the PO ran the battery dead when the fuel lines were leaking, the battery isnt old, but could it have been done in?

TIA

My first thought was battery voltage. The CCU display while useful, doesnt give as good an indication of voltage as a multi meter will.

The PO600 fault may well occur when the display looses communications with the ECU.

I believe the voltage should be 13 or better while running.

I'd suggest checking it with a good meter.

Have you ever replaced the K40 relay? I know it is a shotgun approach to suggest it but that relay controls multiple functions.

Also, I'm not sure when they stopped using the OVP (overvoltage protection relay) but these symptoms sound like that fault too...does anyone know if the '97 uses an OVP?

I guess if it were mine I would start by cleaning every contact I could find on all of the electronic modules in the compartment under the hood...that would at least assure me that it wasn't due to a bad contact connection. I use a product called de-oxit on all of my electrical connectors which cleans and protects them.

Terry and Marty,

Both good ideas. I have noticed on occasion if I have all light, AC, fan on high, that the battery voltage can drop to below 12v while idling. I am thinking the altenator might not be sufficiently charging. I like to do as much work as I can, I may just take the battery back to Autozone, I think its still under guarantee. Will post back with resolutions

Thanks again

Hmmm...yeah those duralast batteries are pretty cheap...I didn't know you used one of them...I'd start there.

I actually would strongly recommend using an OE battery...they are more costly than aftermarket but I have gotten as much as 10 years out of one in the past and feel they are worth the extra $$$ not to have to worry about them.

The OVP of the early and mid 90's was replaced by the K40 relay.

12 volts is too low. I'd def concentrate on the charging system first.

Same here, the OEM batteries are beasts. I used to have a sears diehard and it failed on me, so I got a MB battery at the side of the road....and no problems since.

I have a 96 e300d with a Scangauge installed via the obd port. It gives me constant readings on a number of engine readouts. With the a/c on, my charge rate is 13.4-13.7. Hope that this gives some helpful info.

THanks for the additional posts. The PO had the Autozone battery installed before I bought her. I think I will get a new battery and start from there.

Thanks again

If you have a multi meter,connect it to your battery with the engine running and assuming you are getting a reading above 12v DC switch the meter to AC volts,if you get a reading at or above 1 volt AC there is a bad diode in your alternator.I had a similar problem on my 91 300D where just about every light along the bottom of the instrument panel was lighting up most of the time,the AC voltage was the problem,a new alternator was the cure.
My $.02 Don

Thanks Don, will give it a try this weekend.

Your voltage readings are in-line with mine. It's not until the battery is recharged that at idle the voltage on the ACC will read around 13 volts, mine varies between 12.7-13.3. I wouldn't worry too much about the specific values as there is also apparently a resister in the ACC to limit the voltage going to it to keep it @ a safe level. Correct me if I'm wrong but the alternator should be putting out around 14v...

I've had strange issues w/ my battery in the past, but, how is it starting firt thing in the morning or whenever you drive it? Does it seem weak to crank? If so I would replace the battery to be a good start.... Ever do a VMI @ the stealer to see what your car may have had done at a stealership in the past, could point you what to focus on????

Good point addressing the alternator though....

Michakaveli,

Thanks for the reply. I have all paperwork from PO. The car never saw a dealers service dept. in the whole time she had it. All work was done at an indy on the Eastern Shore of MD. There was an altenator replaced back in 2002. I have never had any cranking issues even when left outside during the winter. Its mostly affected when I do short stop and go trips, or sit in the drive , turn off car, restart and repeat the step a couple of times. The cranking speed never slows down. Same thing happened after changing fuel filters, I had to crank for 20seconds and then the lights stayed on. I shut her down, restarted and all was fine. When its acting normal as soon as car starts your can see the idiot lights get bright just before going out. When it is going to screw up the idiot lights never get bright they stay same, and then the MFA bleeps all the messages associated with the lights. It almost appears as there is a heavy draw after starting that lowers the voltage to below 11 causing the lights to stay on. Funny thing about these cars, there are no altenator lights, I guess I would get a message on the MFA if the altenator fails completely

If the voltage drops too low, you will get a message on the LCD display "Check Charging System".