MIL light is on, bad battery in ECU Ram chip
Discussion
My MIL light recently came on. It was an intermittent thing, but when it got persistent, I checked the ECU log and a battery fault was recorded. The battery mentioned is the one in the ECU Ram chip. I bought a new chip on eBay 2 years ago. The date code on the chip was 2006, already an 9 year old battery ! But it was newer than the one in my Cerb, so I replaced it.
My newer chip (battery) is bad now but why ? As far I know, these chips are not anymore manufactured and most likely l got a chip from an old stock with a new label printed. So watch out for refurbished chips !
My newer chip (battery) is bad now but why ? As far I know, these chips are not anymore manufactured and most likely l got a chip from an old stock with a new label printed. So watch out for refurbished chips !
crypto said:
My MIL light recently came on. It was an intermittent thing, but when it got persistent, I checked the ECU log and a battery fault was recorded. The battery mentioned is the one in the ECU Ram chip. I bought a new chip on eBay 2 years ago. The date code on the chip was 2006, already an 9 year old battery ! But it was newer than the one in my Cerb, so I replaced it.
My newer chip (battery) is bad now but why ? As far I know, these chips are not anymore manufactured and most likely l got a chip from an old stock with a new label printed. So watch out for refurbished chips !
How do you know the fault was for the ECU Ram chip? My newer chip (battery) is bad now but why ? As far I know, these chips are not anymore manufactured and most likely l got a chip from an old stock with a new label printed. So watch out for refurbished chips !
There is only one entry for that in the help file:
BAT FLT
This fault is shown if the battery voltage falls below 11 V, or rises above 17v whilst engine peed is above 1500 RPM.
Battery fault can be caused by:
1. Faulty alternator causing over or under charging.
2. Faulty battery .
3. Poor earths from ECU to battery
4. Poor power feed to ECU from battery.
I that is from the help file for the speed six, so I assume the BAT FLT is Battery Voltage Log Fault.
I keep getting Battery Voltage logged as a fault which seems odd as it never meets the above conditions, it does drop to low 11s when the revs drop very low after resetting the adaptive, but that is well below 1500 RPM.
So if it's really the ECU battery it's taking about it could explain a lot! It seems odd though as in the MEB software it shows the current state of all the sensors & under them on the same page is the logged faults, there is only one for battery & the log fault corresponds to the window above that shows the current car battery voltage.
Luckyone said:
How do you know the fault was for the ECU Ram chip?
I replaced my "new" chip with the original one and the MIL light was gone. To make sure this was the problem I put the new chip in and the fault was back.Luckyone said:
There is only one entry for that in the help file: BAT FLT
This fault is shown if the battery voltage falls below 11 V, or rises above 17v whilst engine peed is above 1500 RPM.
Battery fault can be caused by:
1. Faulty alternator causing over or under charging.
2. Faulty battery .
3. Poor earths from ECU to battery
4. Poor power feed to ECU from battery.
that is from the help file for the speed six, so I assume the BAT FLT is Battery Voltage Log Fault.
You are right, I downloaded the data-sheet of the chip and I can't see a way how the voltage of the chip battery can be measured by the ECU. However, the software could disconnect the power of the chip and check if it holds the data. But this seems very unlikely. This fault is shown if the battery voltage falls below 11 V, or rises above 17v whilst engine peed is above 1500 RPM.
Battery fault can be caused by:
1. Faulty alternator causing over or under charging.
2. Faulty battery .
3. Poor earths from ECU to battery
4. Poor power feed to ECU from battery.
that is from the help file for the speed six, so I assume the BAT FLT is Battery Voltage Log Fault.
Luckyone said:
I keep getting Battery Voltage logged as a fault which seems odd as it never meets the above conditions, it does drop to low 11s when the revs drop very low after resetting the adaptive, but that is well below 1500 RPM.
So if it's really the ECU battery it's taking about it could explain a lot! It seems odd though as in the MBE software it shows the current state of all the sensors & under them on the same page is the logged faults, there is only one for battery & the log fault corresponds to the window above that shows the current car battery voltage.
There must be other conditions to turn the MIL on, if I push the red button the MIL comes on and goes away as soon the engine fires. In my case the MIL never came on during driving, but immediately after starting. My 12V main battery is only a year old, and the engine starts on first try even after weeks of no use. So if it's really the ECU battery it's taking about it could explain a lot! It seems odd though as in the MBE software it shows the current state of all the sensors & under them on the same page is the logged faults, there is only one for battery & the log fault corresponds to the window above that shows the current car battery voltage.
Peter
crypto said:
There must be other conditions to turn the MIL on, if I push the red button the MIL comes on and goes away as soon the engine fires. In my case the MIL never came on during driving, but immediately after starting. My 12V main battery is only a year old, and the engine starts on first try even after weeks of no use.
Peter
Sounds maybe like the chip was causing your MIL light to come on & the battery fault is a different issue. Or did the MIL light & the logged fault go away at the same (when you refitted the good chip)?Peter
I've never had the MIL light come on in normal driving, it only ever does if I stall it & restart it immediately. (I don't often stall it, but did when it was new 14 odd years ago & again now having not driven it for a few years after rebuilding it)
I only noticed the Battery Voltage logged as a fault as I was trying to get the adaptives right, I keep clearing the fault, but keeps coming back for no obvious reason.
It's quite likely my chip / battery is dead as it sat unpowered for at least 4 years while I rebuild the car. PCs battery's tend to be like that. So maybe the chip is linked to that fault in some odd way.
Have you found a reliable source for these chips? I'd be interested to see if it stopped my Battery Voltage logged fault.
The Dallas chips (DS1230Y = 256k Non-Volatile SRAM) simply have a 3V battery on the top, to keep the data intact when the ECU is powered off
[We use them in arcade machines to save the high-scores - another way to use up all my spare time!]
You can either rig in an alternative 3V source to the circuit, buy a replacement SRAM or replace the 3V battery
CR2032 or similar normally do the job, but not sure how brave you might be with this!
Here's a picture of one without the case on
and a brief document on what the chip is and another diagram
http://www.maximintegrated.com/en/app-notes/index....
HTH!
[We use them in arcade machines to save the high-scores - another way to use up all my spare time!]
You can either rig in an alternative 3V source to the circuit, buy a replacement SRAM or replace the 3V battery
CR2032 or similar normally do the job, but not sure how brave you might be with this!
Here's a picture of one without the case on
and a brief document on what the chip is and another diagram
http://www.maximintegrated.com/en/app-notes/index....
HTH!
Peter, have you measured the main car battery voltage with the car running at a few 000 RPM.
THe MIL light comes on at over 17 volts and the alternator voltage regulators in the alternator often fain in a state that lets the alternator reach in excess of 17 volts.
If this is the fault then your car will start but your battery won't last long due to being overcharged.
Correct voltage across the battery terminals with the engine running at a decent speed should be around 13.8 volts.
The regulators often fail along with an old battery due to a defective battery putting excessive load on the regulator.
Regulators normally fail gradually with the MIL light coming on occasionally but then getting progressively worse, a common indicator of a failing regulator is a pulsing of the internal lights and instrument lights.
THe MIL light comes on at over 17 volts and the alternator voltage regulators in the alternator often fain in a state that lets the alternator reach in excess of 17 volts.
If this is the fault then your car will start but your battery won't last long due to being overcharged.
Correct voltage across the battery terminals with the engine running at a decent speed should be around 13.8 volts.
The regulators often fail along with an old battery due to a defective battery putting excessive load on the regulator.
Regulators normally fail gradually with the MIL light coming on occasionally but then getting progressively worse, a common indicator of a failing regulator is a pulsing of the internal lights and instrument lights.
Juddder said:
The Dallas chips (DS1230Y = 256k Non-Volatile SRAM) simply have a 3V battery on the top, to keep the data intact when the ECU is powered off
That's very interesting, I was just thinking if the battery really is dead then the ECU should lose all the adaptive maps when the ignition is turned off I guess? Or is there a permanent 12v feed to the ECU? Or I assume I should be able to measure 3v by just taking the tub off it if it's easy to get off? The battery can not be replaced on these chips, but there are alternative solutions as the example above. I bought mine on eBay, they were about 8£/each. The newer MBE ECU uses a separate (replaceable) battery. These chips have a built in "seal", the battery is internally not connected when new. The first time power is applied, the battery is connected to the circuit (for ever).
According help file a logged error will turn on the MIL until its reset by the Pc software. And where is the log ? Yeah, in the RAM Chip with the battery. With my new chip I had reset the fault several times during this week and since the old one is back in no problems at all.
An other thing crossed my mind, the original chip had 4.75 volts as a minimum operating voltage, the new chip operates down 4.5 volts. Could this cause some uncontrolled writes by the CPU when the main battery voltage drops during starting ? In the ECU this certainly regulated from 13.8 to the 5volts used internally. I'll never know
According help file a logged error will turn on the MIL until its reset by the Pc software. And where is the log ? Yeah, in the RAM Chip with the battery. With my new chip I had reset the fault several times during this week and since the old one is back in no problems at all.
An other thing crossed my mind, the original chip had 4.75 volts as a minimum operating voltage, the new chip operates down 4.5 volts. Could this cause some uncontrolled writes by the CPU when the main battery voltage drops during starting ? In the ECU this certainly regulated from 13.8 to the 5volts used internally. I'll never know
gruffalo said:
Peter, have you measured the main car battery voltage with the car running at a few 000 RPM.
No, as the MIL never came on during driving.gruffalo said:
THe MIL light comes on at over 17 volts and the alternator voltage regulators in the alternator often fain in a state that lets the alternator reach in excess of 17 volts.
If this is the fault then your car will start but your battery won't last long due to being overcharged.
Correct voltage across the battery terminals with the engine running at a decent speed should be around 13.8 volts.
The regulators often fail along with an old battery due to a defective battery putting excessive load on the regulator.
Regulators normally fail gradually with the MIL light coming on occasionally but then getting progressively worse, a common indicator of a failing regulator is a pulsing of the internal lights and instrument lights.
Good to know, I will monitor things with the old chip back in now.If this is the fault then your car will start but your battery won't last long due to being overcharged.
Correct voltage across the battery terminals with the engine running at a decent speed should be around 13.8 volts.
The regulators often fail along with an old battery due to a defective battery putting excessive load on the regulator.
Regulators normally fail gradually with the MIL light coming on occasionally but then getting progressively worse, a common indicator of a failing regulator is a pulsing of the internal lights and instrument lights.
Thanks
Peter
I doubt this problem is to do with that ram chip.
The ECU stores error codes and adaptives in the ram chip, so that removing it and replacing it WOULD be the equivalent of reseting your adaptive and clearing your fault codes.
In other words because it cleared the faults temporarily is because replacing that chip would have done that anyway.
The ECU stores error codes and adaptives in the ram chip, so that removing it and replacing it WOULD be the equivalent of reseting your adaptive and clearing your fault codes.
In other words because it cleared the faults temporarily is because replacing that chip would have done that anyway.
You can get new chips here:
http://uk.farnell.com/webapp/wcs/stores/servlet/Se...
There is an internal lithium battery but you can get a piggy back battery as shown earlier in the thread.
http://uk.farnell.com/webapp/wcs/stores/servlet/Se...
There is an internal lithium battery but you can get a piggy back battery as shown earlier in the thread.
julian64 said:
I doubt this problem is to do with that ram chip.
The ECU stores error codes and adaptives in the ram chip, so that removing it and replacing it WOULD be the equivalent of reseting your adaptive and clearing your fault codes.
In other words because it cleared the faults temporarily is because replacing that chip would have done that anyway.
Tis a very good point.The ECU stores error codes and adaptives in the ram chip, so that removing it and replacing it WOULD be the equivalent of reseting your adaptive and clearing your fault codes.
In other words because it cleared the faults temporarily is because replacing that chip would have done that anyway.
I found my Battery Voltage fault was back again when I plugged the old lap top back in (only a day or so since last time), but I also found the log files in the ECU this time (using the yellow cerb background at the time). They make for fun reading, I've got 58 seconds logged at 7000RPM I'm sure it's not seen 7k in the last 5 years as it's been mainly off the road & has been nursed about in the short time it's had a running engine, so they must go back quite a few years. I assume they must be stored in that chip too? So by that logic I guess the battery in it must be ok.
More useful in this instance is the battery voltage log, that shows it's never been over 14v for the time of that log & there is a hell of a lot of seconds logged at normal voltages, it does how ever show it's spent a surprising amount of time at very low voltages like down to about 6v! It has been though quite a few battery's over the years. I assume that log is at all engine speeds, it's not meant to log faults below 1500RPM. Watching the read out on the laptop now it's always showing at least 13.5v by 1500RPM. I did give the battery a pounding starting it a lot when mucking about with the adaptive the other day. I'll just keep an eye on if for now I think.
Gentlemen, it was certainly not my intention to cause confusion with my original topic/message. What I'm trying to say is, if you observe logged battery faults it could be the ram chip. It was the case in my car. When the problem happens, the MIL and the beeper is permanently on (very annoying if you have a half hour drive home).
When I reset/cleared the logged fault (via the PC software), the MIL and beeper went off too. I had to do this on about 5 occasions and it always came on when I started the car, never during driving. So I replaced the chip with my original one and since that chip is in, the problem has gone too. Nothing else was changed.
Of course the chip holds the adaptives and log when you remove it, and later put it back in its socket, or even if you put it into an other car. But this doesn't matter because I had reset the log fault several times on the bad chip.
If you order a chip, try to get the DS1230AB (which is the original type) and not the DS1230Y. My "bad" one was a DS1230Y, this type protects the RAM if voltage drops below 4.25 Volts and operates from 4.5 - 5.5 Volts (ECU internal supply voltage derived from 13.8V main battery). The limit for the DS1230AB is 4.5 Volts and 4.75 - 5.25 Volts.
Thanks for all input. Peter
When I reset/cleared the logged fault (via the PC software), the MIL and beeper went off too. I had to do this on about 5 occasions and it always came on when I started the car, never during driving. So I replaced the chip with my original one and since that chip is in, the problem has gone too. Nothing else was changed.
Of course the chip holds the adaptives and log when you remove it, and later put it back in its socket, or even if you put it into an other car. But this doesn't matter because I had reset the log fault several times on the bad chip.
If you order a chip, try to get the DS1230AB (which is the original type) and not the DS1230Y. My "bad" one was a DS1230Y, this type protects the RAM if voltage drops below 4.25 Volts and operates from 4.5 - 5.5 Volts (ECU internal supply voltage derived from 13.8V main battery). The limit for the DS1230AB is 4.5 Volts and 4.75 - 5.25 Volts.
Thanks for all input. Peter
Jhonno said:
I keep getting a Batt Log error also.. Yet, it seems to run between 13.1-13.6V mostly, sometimes dipping into the high 12's.. Battery starts fine with plenty of juice, can leave it a few days and it'll still start fine.
Is it supposed to be fairly stable, or all over the place?
Have you ever had the alarm beeper going off as Peter said he had? Is it supposed to be fairly stable, or all over the place?
It's never caused the MIL or beeper for me, but the logged fault keeps coming back, though my battery voltage is the same as yours.
I'm just wandering if it's a slightly different fault or the same one.
If the chip is easy to change there is one way to find out!
Luckyone said:
Jhonno said:
I keep getting a Batt Log error also.. Yet, it seems to run between 13.1-13.6V mostly, sometimes dipping into the high 12's.. Battery starts fine with plenty of juice, can leave it a few days and it'll still start fine.
Is it supposed to be fairly stable, or all over the place?
Have you ever had the alarm beeper going off as Peter said he had? Is it supposed to be fairly stable, or all over the place?
It's never caused the MIL or beeper for me, but the logged fault keeps coming back, though my battery voltage is the same as yours.
I'm just wandering if it's a slightly different fault or the same one.
If the chip is easy to change there is one way to find out!
gruffalo said:
I spoke to someone in the know on the battery voltage fault log and his comment was that "they all do that" voltage when cranking will be much lower than 13 volts, it is not a real fault.
Problem is that on startup of your engine, the coding in the ecu rotates the crankshaft but doesn't start recording low voltage until the engine has fired, so technically I don't think it does sense the drop in voltage for the cranking.From memory I think it only starts looking at the voltage after the car has achieved a magic 100rpm which it sees as 'takeoff' from the starter motor.
Luckyone said:
Jhonno said:
I keep getting a Batt Log error also.. Yet, it seems to run between 13.1-13.6V mostly, sometimes dipping into the high 12's.. Battery starts fine with plenty of juice, can leave it a few days and it'll still start fine.
Is it supposed to be fairly stable, or all over the place?
Have you ever had the alarm beeper going off as Peter said he had? Is it supposed to be fairly stable, or all over the place?
It's never caused the MIL or beeper for me, but the logged fault keeps coming back, though my battery voltage is the same as yours.
I'm just wandering if it's a slightly different fault or the same one.
If the chip is easy to change there is one way to find out!
gruffalo said:
I spoke to someone in the know on the battery voltage fault log and his comment was that "they all do that" voltage when cranking will be much lower than 13 volts, it is not a real fault.
That sounds encouraging I was hoping I could just keep ignoring it as I had been! julian64 said:
From memory I think it only starts looking at the voltage after the car has achieved a magic 100rpm which it sees as 'takeoff' from the starter motor.
The help file says it not meant to log a fault with the battery voltage till the engine is over 1500rpm. But is does seem that is not the case. Jhonno said:
Nope, never had the MIL light/beep going off.
Ah just the same as me then, seems they must "all do that" then! I guess Peters fault must have been a bit different then. Wondering if anyone could help with the following. The topic is also being discussed on the T350 owners page on Facebook currently.
Problem appeared 2 years ago. Occasionally when starting the car, it would crank well and fire into life but instantly die before idle.
It would then struggle to start and if it did start would run lumpy until the adaptives were reset via a pc, then it ran lovely. This would happen roughly 1 in 5 starts.
At a service at STR8 SIx they diagnosed a faulty ECU and replaced it. All was well but looking back it appears the costlty remedy wasnt actually needed.
Fast forward a year and it happened again. Started to happen every 1 in 10 starts until it became 1 in 5.
Matt Smith was close by when it happened once and advised on a Dallas chip change. Ordered one from TVR Powers, fitted it and problem solved.
Fast forward another 4 months and problem has occureed twice now in the last month and I predict will only get worse.
It would seems that somehting is causing the chip to deteriorate slowly and when the car doesnt fire up first time the adapatives maps are lost.
Does this ring true for others and what were the solutions?
Any help appreciated.
Problem appeared 2 years ago. Occasionally when starting the car, it would crank well and fire into life but instantly die before idle.
It would then struggle to start and if it did start would run lumpy until the adaptives were reset via a pc, then it ran lovely. This would happen roughly 1 in 5 starts.
At a service at STR8 SIx they diagnosed a faulty ECU and replaced it. All was well but looking back it appears the costlty remedy wasnt actually needed.
Fast forward a year and it happened again. Started to happen every 1 in 10 starts until it became 1 in 5.
Matt Smith was close by when it happened once and advised on a Dallas chip change. Ordered one from TVR Powers, fitted it and problem solved.
Fast forward another 4 months and problem has occureed twice now in the last month and I predict will only get worse.
It would seems that somehting is causing the chip to deteriorate slowly and when the car doesnt fire up first time the adapatives maps are lost.
Does this ring true for others and what were the solutions?
Any help appreciated.
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