Join Now
International Automotive Technicians Network
1998 Nissan Pathfinder 3.3L Intermittent No Start
Posted to Technical Tips Forum on 9/5/2011 19 Replies

Tip: Injectors do not operate while cranking, check the EGI (main) Relay.

A shop I occasionally deal with called and asked for direction on an intermittent no start on a Nissan Pathfinder. The tech asked how I would start diagnosing the problem. I told them that he should check scan data and make sure that nothing is grossly out of spec, such as TPS, Coolant Temps, RPM, or Injector Pulse Width. Just look for something usual. Make sure there's nothing going on with the security light. Check fuel pressure and volume. Check for spark. The tech said the vehicle had fuel pressure and spark, but no injector operation. I asked how they determined that and they said that the injectors were not clicking. He said he would check what I had suggested.

The tech drove the vehicle to my shop unannounced, and told me to take my time diagnosing the problem. I asked the tech if they checked scan data, and he said

"It has no codes."

I asked if he checked the TPS and Coolant Sensor values, and he said

"They should be fine, we changed those parts".

I said, "We start with 1.5 hrs up front". "You can watch and help if you want while you wait for your ride". I hooked up my Solus Pro scanner and found none of the PIDs out of spec. I tried cranking the vehicle over, but it wouldn't start. I checked the #1 injector control circuit and I could see the PCM pulling the circuit to ground, but there is no spike when the driver turns off. I then dual traced the power and control circuit at the injector with my Vantage Pro, and this is what I saw.

[1998 Nissan Pathfinder LE, ECM/Inputs/Outputs Waveform]

Looking at Alldata, it shows that the EGI relay powers both the PCM and the Injectors. It's a 5 Pin relay, and apparently there are 2 switches/circuits within the relay to power the PCM and Injectors separately.

I took a #2 Phillips Dark Blue Snap On Screwdriver, (There is a difference) and used the handle to tap the top of the relay while the tech from the other shop cranked the engine over, this is what happened.

[1998 Nissan Pathfinder LE, ECM/Inputs/Outputs Waveform]

I told the tech he probably could have used a DMM and a test light to diagnose this problem. He said he used a "noid" light and it did flash dimly. He thought that the PCM could have been bad, but he didn't want to go there.

A hot test light on the control side would have resulted in a bright flashing light while cranking. If he used a grounded test light on the control side it would have resulted with a very dim or no light. At that point he could have monitored the "hot" side with either the test light or DMM. KOEO with the multimeter would have shown battery voltage, but connecting a test light to that circuit would have brought the voltage down. Then he could have looked in a wiring diagram as to where the power came from. Tapping the relay would have resulted in a bright test light. He said,

"Wouldn't be easier just to change the relay instead of doing all that testing?"

Right, so I put up this tip.

Danny from California

Files Referenced:

thumbnail thumbnail

19 Replies Received (View Replies)


car Vehicle Data

1998 Nissan Pathfinder LE 3.3L

Engine3.3 L
Trans4-speed Automatic (Electronic)