Glow issue 2005 Navara

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JasenJ

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Hello,

I recently bought a nissan navara with some issues. The car has shifted owners because no one has been able to figure out exactly what the problem is.

The car wont start in its orginal state so the previous owner has installed a secondary battery and connected it to the starter, now it starts only when cold start swich is on.

I did some testing and found out that the glow plugs dont get power when i turn ingnition on, however when the car starts they get battery voltage. if i turn off the cold start switch glow plugs still get power, BUT if i press the clutch the power is gone and engine stalls.

Also i get an error code P0686 ECM voltage low

Anyone got any ideas?
 

izzibri@gmail.com

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What the P0686 code means. The P0868 code is a standard OBD-II trouble code that notes a voltage error with the "RELAY"" control circuit that is responsible for supplying the powertrain control module (PCM) and engine control module (ECM) with power.have you got a faulty relay , i sometimes switch relevent relays, often you will have relays with same part number.. Check ALL your earth cables. make sure that they are all there,.i had one to manifold, the bolt had a stripped thread, also one cable was frayed . noticed you said need 2 batterys to help it start , is your starter on its way out , i had to change mine , when i noticed engine was turning slower and was harder to start even with a new HD battery, when i connected a second battery engine would turn slightly faster .. this would cause a voltage draw problem as soon as you engage the key and could upset the electronics.. just something to consider
 

JasenJ

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The cable from the original battery to the starter is dissconnected and the "new" battery is only supplying power to the starter. starter is brand new.

Im going to look into the grounding issue you mentioned and hopefully I will find something, otherwise the harness is coming out :cry:
 

izzibri@gmail.com

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on engaging ignition ,the exiter glow plug light on your dash is what activates power supply (no light no power) ,you should be able to hear the relay clicking on the power supply unit, which send power to your glow plugs.( you may need to be listenning in engine bay get some one to activate your ign . if power is going in it should come out.. it sounds like your power supply unit is malfunctionning . i did a manual bypass on one of my engines by using 60 amp start button and heavy wirring direct to glow plug rail ,, a great way to burn your plugs if you engage for more than 4 seconds at a time
 

tweak'e

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Hello,

I recently bought a nissan navara with some issues. The car has shifted owners because no one has been able to figure out exactly what the problem is.

The car wont start in its orginal state so the previous owner has installed a secondary battery and connected it to the starter, now it starts only when cold start swich is on.

I did some testing and found out that the glow plugs dont get power when i turn ingnition on, however when the car starts they get battery voltage. if i turn off the cold start switch glow plugs still get power, BUT if i press the clutch the power is gone and engine stalls.

Also i get an error code P0686 ECM voltage low

Anyone got any ideas?
P0686
ECM relay circuit
ECM detects ECM relay is stuck closed even if ignition switch OFF.
Harness or connectors (The ECM relay circuit wiring is shorted.)
 

Boogieboots

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I am curious about the clutch thing mentioned in the original post. Is there a switch for checking clutch engagement? What would that be for?
 

JasenJ

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Yes there is a switch on the pedal, In cold start mode it brings the revs up to 1400 rpm and when you press the clutch it brings it back to normal
I am curious about the clutch thing mentioned in the original post. Is there a switch for checking clutch engagement? What would that be for?
Yes there is a switch on the pedal, In cold start mode it brings the revs up to 1400 rpm and when you press the clutch it brings it back to normal
 

JasenJ

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Does anyone know if there is some software that allows you to connect to the ECM and reprogram it/ mess it up?
 

Rumpig

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Can't be done without desoldering the 2 chips in the ecu and having the software and chip burner necessary to do the read/write.
 

JasenJ

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So i discovered something interesting. I decided to try and jump start the car and do some measurements at the same time, turns out when i get 14v instead of 12v everything works as it shold. glow light tuns on when ignition is on and the car starts no problem. Im wondering if the glow releay could wear in such a way that it requires more power to engage. this would explain the weird behavior that when the car is running the glow relay gets 14v from the alternator.
 

Rumpig

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If the ecu see's less than 11V it shouldn't start.
 

izzibri@gmail.com

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That low voltage code is correct you proved that by readings when you jump start.Just a thought are all the extra cables that are on both the old terminals been transfered to your new battery. could the problem be a cooked fuseable link (will affect the draw amperage) this link could be supplying power preheat unit, it may also have its own earh cable back to battery or to body.when engine starts and system is charging that link is bypassed.
 

JasenJ

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That low voltage code is correct you proved that by readings when you jump start.Just a thought are all the extra cables that are on both the old terminals been transfered to your new battery. could the problem be a cooked fuseable link (will affect the draw amperage) this link could be supplying power preheat unit, it may also have its own earh cable back to battery or to body.when engine starts and system is charging that link is bypassed.
I have bought a new fusable link (from ebay) and replaced it, it was supposed to be oem part but turns out that some of the fuses are larger amp rating but im not too concerned about that. I took out the dash board and checked the earts befind it, also checked the ones in the engine bays. I get battery voltage to ECM (port 119 and 120) I also measured the woltage drop when staring and it goes down to 11.88V on the battery terminals.
 

izzibri@gmail.com

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when you say that theres a second battery, you have 2 batteries is the first battery on its way out, it may show charged but has very little draw power, is the pre heat unit connected to this one .. CHECK how the 2 batteries are connected. just a thought probably irrelevant , had a problem with voltage drop where there were 3 earth cables , had 12 volt at first globe then 6 volt on second globe which was very dim. power was going through 1st globe then through the earth cable to second bulb. the oxidized connection was between earth cables .. Is it worth connecting just one battery as original and see if there is a exessive voltage drop on starting.. (wirring short somewere)
 

JasenJ

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So i was looking at the wiring diagram and found this swich. It says that when pedals are released there should be battery voltage to the ECM. Im no electrician and i dont know how the ecm works but could it be that if there is a short there the car wont start
 

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Rumpig

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The ecu does use signals from the brake and clutch pedals but the car will start whether they are pressed or not , so a faulty switch on either won't prevent it starting.
 

JasenJ

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The ecu does use signals from the brake and clutch pedals but the car will start whether they are pressed or not , so a faulty switch on either won't prevent it starting.
Good to know. It's weird that the engine stalls as soon as i press either pedal after starting. This only happens when glow plugs are on
 

izzibri@gmail.com

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i think you are looking in the correct area. have the 2 switches got different connectors couldnt be interchanged has some one changed a switch with incorrect one,, those type of switches are either normally open or normally closed.. incorrect type would cause malfunction.. in that circuit has some one spliced a wire to connect some thing else
 

Rumpig

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After market cruise controls are wired through the clutch and brake pedal , hasn't had one fitted?
 

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