Nissan Armada & Infiniti QX56 Forums banner
1 - 7 of 7 Posts

· Registered
Joined
·
366 Posts
Half-start issue seems to be directly related to lower battery voltage, short trips, and restarting within a short time of shutting off.

It happened to me for my 2nd time in 2 years this past weekend. I shut the vehicle down after about 3 hours of driving. And then attempted to restart within about 30 seconds, unplanned but I had to move the vehicle.

I also tend to think it's when the brake and start button sequence is rushed or button not fully depressed for a solid 2 seconds. I likely jumped right back in and rushed the sequence, maybe even pushed both brake and button simultaneously.

Either way, our charging systems don't help and are bad for battery health. Look into bypassing the voltage sensor on the negative terminal.
 

· Registered
Joined
·
366 Posts
I have not had this issue happen again since I disconnected the sensor on the battery terminal.
Mine did it twice over the course of about 2 months in summer of 2020.

Since disconnecting the battery sensor we have put about 15k on the Armada, towed our 28' camper regularly (1 trip in excess of 2k miles), been to SC, Western NC, and VA. It has not happened once; long trip, short trip, hot or cold. I am going to chalk this one up as being directly related to battery voltage.

The short trips seem to be a trend for the problem to happen as well as heat, but I believe the heat just compounds the low battery voltage issue as the starter is less efficient when it's hot.
Short trips do not allow the battery to charge up after a start, but the real problem is that with the sensor connected your ECM is always keeping the battery charged at too low of a voltage anyway.

With the battery constantly maintained over 13 volts it can handle the shorter trips and repeated starts.
IMHO disconnecting the battery sensor has cured this and has zero adverse results.
YMMV, I am not a mechanic.
 

· Registered
Joined
·
366 Posts
@Len T it is a sensor that it attached directly to the negative terminal on the battery itself. There is only 1 harness that goes to this sensor. I'm sorry but I do not have an easily accessible picture at the moment. There is likely one in another sub-forum.

When plugged in, the ECM talks to this sensor and limits the battery charging to the minimal amount possible to maintain right around 13 volts. This is all done in the name of 1/10 of an increase in MPG. The problem is that batteries really need to charge around 14.2 volts. If you only charge to 13, your static voltage is usually 12.6 or lower. If you allow the alternator to charge to 14.2-14.5 your static voltage is always 13 or higher on a healthy battery.

If your battery is only at 12.6 static, once a load is applied it may drop to 11.8 or lower. Vehicle electronics in general do not like to see under 11.8. So in theory if the vehicle is attempting to start right on that threshold you could run into some pretty wonky effects.
 

· Registered
Joined
·
366 Posts
Charge the battery up to a healthy voltage with a good charger.

Disconnect the sensor on the negative terminal.

Don't rush the brake and push-button sequence.

I haven't had this issue come back in over 18 months.
 
1 - 7 of 7 Posts
Top