Truck help (1995 Nissan hardbody)

[Bantou]

Have any of y’all had an issue with parasitic drain and stalling? I have a 95 Nissan hardbody that has a draw on the circuit that runs the fuel pump and I think dash lights.

The relay stays warm to the touch even after the truck has been off for a while and the drain stops if the relay is removed. It will stall and restart itself at low rpm but seems to do fine at higher rpm. When it stalls the dash lights blink.

The relay is new but past that I’m not sure what else has been done to it. I know it has been to the mechanic several times but I’m not sure what all they checked (the truck belongs to my parents and I’m trying to get it running again).


Sent from my iPhone using Tapatalk

[Winger Ed.]

That's a head scratcher.

I don't drive much, and our '02 & '06 are just now getting into the problems people had with them when they were 2-4 years old
with 'normal' mileage.

When I have a problem I can't figure out, I got to the archives of car forums with a search engine.
It's usually there where somebody else had the same problem 10 years ago, and there is long discussions on fixing it.

I see solutions I'd never have thought of.

Like your relay- it probably isn't the problem.
It might be whatever is telling it to stay on when it shouldn't.

[rancher1913]

there is a sensor someplace that activates that relay, that may be your problem.

[Bantou]

That's a head scratcher.

I don't drive much, and our '02 & '06 are just now getting into the problems people had with them when they were 2-4 years old
with 'normal' mileage.

When I have a problem I can't figure out, I got to the archives of car forums with a search engine.
It's usually there where somebody else had the same problem 10 years ago, and there is long discussions on fixing it.

I see solutions I'd never have thought of.

Like your relay- it probably isn't the problem.
It might be whatever is telling it to stay on when it shouldn't.

I have tried google with limited success. Unfortunately surging/stalling and battery drain are very common symptoms of a variety of problems. I’ll check out the wire diagram again and see if I can’t find where the signal comes from. Thanks for the pointer.


Sent from my iPhone using Tapatalk

[Bantou]

there is a sensor someplace that activates that relay, that may be your problem.

I’ll look at the diagram again and try and find it. It’s a good place to start the hunt. I hate electrical problems. You can spend hours chasing red herrings and then find it in 15 minutes by chance.


Sent from my iPhone using Tapatalk

[Winger Ed.]

I’ll look at the diagram again and try and find it. It’s a good place to start the hunt.

Something upstream is not telling that relay when its time to shut down.

If the newer Nissans are anything like my '86 pick up with a V-6:
It'll be something weird too, a sensor you wouldn't think was in the loop,
or even something in the guts of the ignition key switch.

[abunaitoo]

I'm almost sure the fuel pump and dash lights are on different circuits.
By parasitic drain, do you mean it's draining the battery when the engine is off????
There will be a small parasitic drain because of the computer.
Have you tried pulling fuse to find which circuit the parasitic drain is on????
Relays will be warm to the touch, but shouldn't be hot.
Are you sure it's a fuel problem????
Check the cap, rotor and wires.
"When it stalls the dash lights blink."
Might be a bad ground wire someplace.
They cause all kinds of intermittent problems.
Never saw dash lights blink when an engine stalls.
Something new.
If it is blinking, something electrical might be losing contact someplace.
I kind of remember older Nissan 4x4, used to have some kind of speed control with the 4 low engaged.
Just some thoughts anyway.

[Petrol & Powder]

The parasitic drain and the stalling may be two completely unrelated issues.

The draw on the battery is a bit easier to find by pulling fuses one at a time until you isolate the circuit involved. I've also seen people claim they had something pulling power when in fact what they really had was just a battery on its last legs.

As for the stalling issue, 1995 is plenty old enough for fuel problems to appear. When you say it stalls and re-starts itself, what exactly is happening? Does it occur under load? Or anytime ?

When you say "Dash Lights" - what exactly are you talking about? Warning lights? The lights that illuminate the instrument cluster? ??

Based on the limited amount of information available, it's hard to say what the problem is. A fuel filter or the fuel pickup in the tank could be plugged. (it is a 25 year old truck). There could be an intermittent electrical issue. I would look at the body ground first.

[Frosty Boolit]

Check to see if there is voltage between the coil terminals when you remove the relay. If so, you will have to use a diagram to figure out where it comes from. Could be a ECM output of directly off ignition switch like others have said.

[Bantou]

The parasitic drain and the stalling may be two completely unrelated issues.

The draw on the battery is a bit easier to find by pulling fuses one at a time until you isolate the circuit involved. I've also seen people claim they had something pulling power when in fact what they really had was just a battery on its last legs.

As for the stalling issue, 1995 is plenty old enough for fuel problems to appear. When you say it stalls and re-starts itself, what exactly is happening? Does it occur under load? Or anytime ?

When you say "Dash Lights" - what exactly are you talking about? Warning lights? The lights that illuminate the instrument cluster? ??

Based on the limited amount of information available, it's hard to say what the problem is. A fuel filter or the fuel pickup in the tank could be plugged. (it is a 25 year old truck). There could be an intermittent electrical issue. I would look at the body ground first.

The stalling/starting cycle only happens while driving, not at idle. The best that I can describe it is push starting a standard (which it is) it will stall out and then heave and restart itself like when you dump the clutch on a rolling vehicle to start it. The dash lights I’m referring too are the ones that illuminate the dash. The battery had been replaced twice since the issue began. We know that it is happening on the relay that feeds the fuel pump. I’m pretty sure that relay also runs the dash lights but I will have to look at the diagram again to be sure.


Sent from my iPhone using Tapatalk

[Petrol & Powder]

I don't believe the fuel pump relay will be in the same circuit as the lights. The lighting system generally consists of the headlights, taillights, marker lights, license plate light and instrument lighting. The brake lights are generally on their own circuit (usually not switched through the ignition circuit). The turn signals are generally on their own circuit and are switched through the ignition circuit so they go off when the key is turned off. Courtesy lights (dome light, glove box, cigarette lighter, etc. ) are usually on their own circuit and fused.
Fuel pump relays are always powered through the ignition switch so that the fuel pump goes off when the key is turned off.

Any chance a mouse chewed through a part of the wire harness? That intermittent failure sounds more like an occasionally OPEN circuit rather than an occasional short circuit.

[Bantou]

I don't believe the fuel pump relay will be in the same circuit as the lights. The lighting system generally consists of the headlights, taillights, marker lights, license plate light and instrument lighting. The brake lights are generally on their own circuit (usually not switched through the ignition circuit). The turn signals are generally on their own circuit and are switched through the ignition circuit so they go off when the key is turned off. Courtesy lights (dome light, glove box, cigarette lighter, etc. ) are usually on their own circuit and fused.
Fuel pump relays are always powered through the ignition switch so that the fuel pump goes off when the key is turned off.

Any chance a mouse chewed through a part of the wire harness? That intermittent failure sounds more like an occasionally OPEN circuit rather than an occasional short circuit.

It’s possible. They live out in the country and the truck was mainly used like a UTV for misc farm work. It wasn’t uncommon for it to sit for several weeks between uses. I know those trucks are prone to loose grounds as well.


Sent from my iPhone using Tapatalk

[Petrol & Powder]

It’s possible. They live out in the country and the truck was mainly used like a UTV for misc farm work. It wasn’t uncommon for it to sit for several weeks between uses. I know those trucks are prone to loose grounds as well.


Sent from my iPhone using Tapatalk

OK, that paints a better picture. I would look for damage to the wiring harness. You may want to look under the dash AND under the passenger seat. The ECM for that truck is on the floor under the passenger seat. Those vehicles are pre- OBD-II but you can run a test by turning a switch on the ECM and counting the number of times the check engine lights flashes. The ECM has a cover that must be removed and the switch requires a screw driver to turn it.

I suspect some rodent has chewed up some wiring, probably inside the cab.

[Bantou]

Thank you for taking the time to help me diagnose it. I’ll try and take a look at it over the long weekend and let you know what I find.


Sent from my iPhone using Tapatalk

[jonp]

You can buy a Bluetooth plug in for the obd that syncs to a phone for under $20. I bought the obd 2 for my 97 CR-V and found the problem the engine light lit up for. Many free APS to read them

[Bantou]

You can buy a Bluetooth plug in for the obd that syncs to a phone for under $20. I bought the obd 2 for my 97 CR-V and found the problem the engine light lit up for. Many free APS to read them

I believe it pre-dates the OBD2 but I’ll look into it.


Sent from my iPhone using Tapatalk

[Scrounge]

You can buy a Bluetooth plug in for the obd that syncs to a phone for under $20. I bought the obd 2 for my 97 CR-V and found the problem the engine light lit up for. Many free APS to read them

ODB2 doesn't work on 1995 or earlier vehicles. It's for 1996 & later. I've found several procedures for reading the codes, but from reading his description of the problems, it doesn't sound like that's going to help much. Putting an ammeter in the circuit to read power draw, and pulling fuses until you stop the power draw would isolate the problem circuit. Then Ohms tests, ground checks, and visual inspection of the wiring will probably find the problem(s). It is possible there is more than one, so if you find one, fix it, then keep testing circuits until all are good.

[Petrol & Powder]

It does pre-date OBDII.

But I would push the passenger seat back and take a good look at the wiring harness for the ECM and then look under the dash. I'll bet good money some rodent has chewed through something important.

[Bantou]

Ok I went over and took a look at the truck today. The issue was not on the fuel pump relay but on the EGI relay. After a little Google-fu, all signs point to a bad mass airflow sensor. I have a new one ordered that should be here Tuesday. I’ll post another update once I get it installed.


Sent from my iPhone using Tapatalk

[Scrounge]

It does pre-date OBDII.

But I would push the passenger seat back and take a good look at the wiring harness for the ECM and then look under the dash. I'll bet good money some rodent has chewed through something important.

That is why I suggested visual inspection. Because you're absolutely right, and rodents are often THE cause of wiring problems. Little beggars love the insulation, and there isn't enough current flow even in a live circuit on a car to hurt them.