2010 Nissan Pathfinder

4.0 V6, automatic, 2WD

Problem: Cranks, but doesn't start when cold.

I think the previous owner of this Pathfinder sold it because he couldn't figure out the problem since he did actually disclose that problem before selling it. I saw this Pathfinder shortly after it was bought and the battery wasn't old but was over-filled, so the acid was too diluted.

After a month or so, I got the opportunity to diagnose the cold no-start problem.

The first thing I wanted to blame it on was the aftermarket alarm system. It was installed with clip-on wire splices. One splice was loose. But I resisted the temptation to blame it on that without any condemning evidence.

I thought that warming up the security system module would make a difference. It didn't.

My next thought was a bad temperature sensor might be reading hot and the computer wouldn't give it enough fuel when cold. So I scanned the temperature sensors and didn't find that problem. The MAF is combined with the intake air temperature sensor, so if you have the key on and wait a while to start, it'll read 10 or 20 degrees hotter than ambient because the MAF has a hot wire sensor and it'll read hotter than ambient when there's no air flow.

I sprayed some starting fluid in the intake and it didn't help it start at all.

I checked for spark and the computer wasn't firing the coils.

I noticed that somebody damaged the relays. Eric O. (South Main Auto Repair) saw the same thing on another Nissan.

The relays still worked, so I left them as-is. The relay I'm holding in the above picture is for the radiator fan.

I scanned all the modules for codes and came up with a few, but none that would explain the no-start condition.

Codes

ECM

P1564 - automatic speed control device. Improper voltage signal from steering switch sent to ECM. Each cruise control button has a different resistance. The ECM uses the voltage to determine which switch was pressed. No longer an active code. Maybe this code can be triggered by pressing multiple cruise control buttons at the same time.

P0113 because I unplugged the MAF/intake air temp plug.

IPDM - no DTC

Smart key module not present.

Automatic drive positioner not present (not 4WD).

Intelligent master not present.

Body control module - no DTC.

All four tires TPMS read 0psi.

HVAC module not present (manual controls).

Combination meter no DTC

U1000 (historical)

MIL LED not working.

Airbag LED not working.

Rear camera not present.

Airbag module

B1054 – driver airbag module open

B1049 – driver airbag module open

B1015 – Passenger Deploy. Loop Resistance High.

B1220 - manufacturer defined (I can't find this one.)

It kind of looks like the vehicle was in an accident and they didn't put airbags back in.

ABS module

C1156 – LF wheel speed sensor circuit open

U1000 – communication error

C1163 – steering angle sensor in safe mode

Differential lock module not present.

Automatic transmission module not present. (Not included if no Bose audio system. Weird, I know.)

More Troubleshooting

I connected my battery charger and went to print off some wiring diagrams. The weather got warmer and when I got back, it started right up. So I figured I was done for the day and would try again when it was colder. By the way, the battery was replaced about a month or so ago by the new owner.

I noticed that on the instrument cluster, the SERVICE ENGINE SOON light didn't come on with the ignition in the on position. The airbag and TPMS lights also didn't come on. This instrument cluster doesn't have light bulbs. It uses LEDs without light bulb sockets. So I made sure that the power wire that activates the SERVICE ENGINE SOON light was working. It gets power to connector pin 16 with the ignition on. So that was good. I didn't take apart the cluster to see if the LEDs were sabotaged.

Next, I needed to make sure the ECM was getting power to pin 109 (IGNSW) with the ignition switch in the on position. That also checked out.

I checked the resistance between CAN high and CAN low with the battery disconnected. It read 60.9 ohms, right on target.

Maybe there's a parasitic draw on the battery. I was reading 105mA.

Fuse 21 had a 0.2mV drop, but it didn't have a significant current.
IPDM 50A fuse draws 46mA until the body control module shuts down.
The aftermarket alarm draws about 10mA.
Eventually, the entire system will draw between 27 and 31mA after the modules shut down. I didn't measure the time it took to shut down all the modules. It could be an hour.

Critical Clue

After a few days of troubleshooting, the vehicle's owner told me that it would start with a jump-start. Wow, I wish I knew that a few days ago.

So I determined a new direction for troubleshooting.

Peak starter current draw = 271A. This is a new starter. I had my video camera on the current meter, but as luck would have it, I didn't have it set up correctly to show the average current draw.
Body to engine voltage during cranking = 44mV
Battery negative to body voltage when cranking = 211mV
Battery voltage during cranking = 9.9V
Scantool voltage during cranking = 8.5 - 9.8V.
ECM voltage during cranking: It does not report data when it won't start. If it sends data, it starts.

In this graph, the scan tool voltage scale is on the left, in Volts, and the ECM voltage is on the right in mV. This graph is from when it started. Scan tool volts dropped to about 9.6V. The ECM dropped to 10.5V as reported.

So, knowing that it would start with a jump, I turned on the lights for a minute or less and tried again. This time, it didn't start and the ECM would not report anything while cranking. But as soon as I stopped cranking, it would start sending voltage data again.

Terminal Cleaning

The fusible link assembly on the positive battery terminal looked ok, but I wanted a closer look.

When I disconnected the cables, I saw some corrosion.

I cleaned these up.

I then applied anti-corrosion spray.

There's a body ground connection at the base of the battery. I cleaned that one up too and sprayed it.

Post-Cleaning Voltage

With a fully charged battery and cleaned terminals, here's what the voltage looked like during cranking. Scan tool went down to 10.2V and the ECM went down to 10.5V during cranking.

The two voltages are also closer together now during cranking.

Conclusion

The battery with only 550 CCA was insufficient to keep the Voltage high enough for the ECM to function during cranking. I'm recommending a 1000 CCA battery.

When the voltage drops too low and the ECM won't run, further cranking will only drain the battery. It's best to stop and get a jump start.

It took me a week to figure out that the battery was under-sized.

Cleaning the contacts helped, but I would be nervous about that small battery not starting it when it's super cold outside.