Jump to content
SAU Community

Recommended Posts

Hey everyone my battery light came on last night in my R34 while I was driving around town and I got to see it for a few seconds before all of a sudden my revs just died out and my car died, then immediately came back to life. The light would then intermittently turn on and off and the car died once or twice more then it stopped, and for about an hour nothing happened, it just drove normal. After this hour it happened again when I was just about home so I parked up and have left it alone today.

I tested the alternator this morning and it was charging at 13.8v and I checked my battery and that was holding 13.8v also while the car was running. Does anyone have any ideas of what this could be?

Mods:

RB25/30

ViPEC

Plazmaman Plenum

3076 on a 6boost Highmount

50mm Turbosmart Wastegate

Sard Injectors

Intank 044

Battery Mounted in boot (I checked the earths and connections on this and they looked good)

Any help will be appreciated.

Thanks

Also check your charge rate with your high beams, a/c fan, and brake lights on.

Need to see what the charge is doing under load.

Could still be a faulty alternator, possibly voltage reg on its way out.

But as mentioned, check your battery terminals, and earth points first.

Then go from there.

Good luck.

Sounds like the alternator or volt reg.

Really need a dc clamp meter to test it properly. Volt meters are handy but can give rricky/false readings.

if it was the alternator or reg the engine wouldnt die immediately as it still has the battery to run off. ecm would prob switch off between 8-10 so there would be ample time

sounds like something loose or even a short in batt cables

Hey guys, checked all those things and everything seems fine. The light came back on yesterday and so I tested the alternator and it was only charging at 11v. So I'm going to get it replaced as it seems to be an intermittent problem with that.

check the belt tension aswell? could be slipping

Once more, intermittant alternator wouldn't cause the engine to cut out like the OP describes... It would continue to run just fine off the battery for many more km's until the battery voltage drops to something crazy low like 8v or whatever the ECU starts getting confused at.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
    • Nah, that is hella wrong. If I do a simple linear between 150°C (0.407v) and 50°C (2.98v) I get the formula Temperature = -38.8651*voltage + 165.8181 It is perfectly correct at 50 and 150, but it is as much as 20° out in the region of 110°C, because the actual data is significantly non-linear there. It is no more than 4° out down at the lowest temperatures, but is is seriously shit almost everywhere. I cannot believe that the instruction is to do a 2 point linear fit. I would say the method I used previously would have to be better.
    • When I said "wiring diagram", I meant the car's wiring diagram. You need to understand how and when 12V appears on certain wires/terminals, when 0V is allowed to appear on certain wires/terminals (which is the difference between supply side switching, and earth side switching), for the way that the car is supposed to work without the immobiliser. Then you start looking for those voltages in the appropriate places at the appropriate times (ie, relay terminals, ECU terminals, fuel pump terminals, at different ignition switch positions, and at times such as "immediately after switching to ON" and "say, 5-10s after switching to ON". You will find that you are not getting what you need when and where you need it, and because you understand what you need and when, from working through the wiring diagram, you can then likely work out why you're not getting it. And that will lead you to the mess that has been made of the associated wires around the immobiliser. But seriously, there is no way that we will be able to find or lead you to the fault from here. You will have to do it at the car, because it will be something f**ked up, and there are a near infinite number of ways for it to be f**ked up. The wiring diagram will give you wire colours and pin numbers and so you can do continuity testing and voltage/time probing and start to work out what is right and what is wrong. I can only close my eyes and imagine a rat's nest of wiring under the dash. You can actually see and touch it.
×
×
  • Create New...