[Retiredad]

DIRECTED to:
beodawn1 Which ones would I try to jump?

I have similar issues with unexplained setting of alarm. I assume the system is very similar across the years. Mine is 2000. I've seen it corrected by unlocking doors or disconnecting battery

• The FSM for electrical is easy to get and the wiring diagrams are VERY useful.
• The SECU is responsible for setting the alarm based on MANY inputs it receives.
• The SECU sends signal through terminal 32 (starter cutout) to the TWR terminal 1
• IF, IF, IF you want to disable the starter cutout and nothing else, open that connection at the terminals or cut the wire (R/W red/white) (Wisdom says do so in a way that you can reconnect) This would kill any false or ghost signal to or from SECU.
• Removing the relay will also disable the start circuit.

FSM says: Canceling the Set Theft Warning System: When the doors are unlocked with the key or multi-remote controller, the armed phase is canceled. It's more important to first determine if this part of the TWR/SECU is working. Mine will unlock from LF, RF and REAR key switches.

Did you try all doors? Did you try disconnecting the battery? If so, I would replace TWR before I bypass it. If that doesn't work, I'd look toward the PNP switch as a last resort.

 

[Retiredad]

That was a good question about the trans, with manuals there is a clutch switch in the starter interrupt.
I feel for you with the happy wife, happy life situation. I'm still trying to help.

Did you try unlocking doors or disconnecting battery?

I'm still getting intermittent and strange lock, unlock situations and I would like to disable the alarm also. If I were to modify the relay, as I stated above, break the connection to terminal ! of TWR. This eliminates the signal to arm the alarm. (or break connection to terminal 2, pos side of coil) I would prefer to cut a wire that I can splice back together. I've considered breaking the lug off of the relay but I know my relay works, so why damage it.
If you can get it to disarm, you know it works. If you determine it is not disarming, then nothing to lose by modifying it. Although, IF that doesn't work, you have to have a new relay in there to complete the starter circuit.

 

[Retiredad]

I tried to cross over the “3 and 4” in the fuse box. The key was in my pocket and according to the manual that dad was reading that fuse area should not have had power until I turn the ignition switch to on.

In my diagram power goes directly from the fuse to one side of the coil. (NOT through the key on) The coil is energized when it gets a ground signal from term 32 of SECU.

 

[Retiredad]

Silly me, I thought all xterra's were 4WD.

My experience with FSM from Nicoclub is quite different. Clicked 2000,clicked xterra, opened pdf, clicked download within the pdf, saved on my desktop. Did this for maybe 5 manuals.

I find the diagrams to be accurate but require laser focus on their logic, , kinda like reading between the lines. Or reading it 10 times before you see something you missed.
Or staring at diagram of wiper park switching for an hour. Or trying to think "smart" like an SECU.

For example:
Key Reminder When performing a door locking operation (early production models) using either the main power window and door lock/unlock switch, the door lock/unlock switch RH, the front door LH lock knob or a multi-remote controller,
all the doors will lock and then will immediately unlock
if the
key switch is in INSERTED position (key is inserted into ignition key cylinder) and
ignition switch is in the OFF position and
either front door switch LH or RH is in OPEN position (door is open).

When performing a door locking operation (late production models) using either the main power window and door lock/unlock switch, the door lock/unlock switch RH, the front door LH lock knob or a multi-remote controller,
all the doors will lock and then the front door LH will immediately unlock
if the
key switch is in INSERTED position (key is inserted into ignition key cylinder) and
ignition switch is in the OFF position and
either front door switch LH or RH is in OPEN position (door is open).
all the doors will lock and then the front door LH will immediately unlock

This caught my eye. (More later)

 

[Retiredad]

Hey, I might be absent minded, but that's my choice.
Like setting an alarm when I want to set it. Not every time the "smart" doors lock.
Or taking my chances on avoiding a skid, instead of ABS telling me my wheel speed inaccurately, when I'm going 3 mi//hr.
Or taking my chances on hearing a ping from bad gas and do something about it, instead of a faulty sensor retarding my timing and not telling me unless I ask for codes.
Go ahead and shoot me if I ever buy a vehicle that turns itself off at a stop sign. LOL

 

[Retiredad]

Yep, prevents keys from getting locked inside in those situations.

Amen to that, however if you add multiple modules, actuators, cylinders, low voltages, corrosion and migration, and human error, it "opens the door" to a can of wormholes that could cause a lock signal to set the alarm unknowingly or leave a door unlocked thus triggering interrupt.

And now it's time to consider the 30 second delay before the armed flashing sequence ends. Does the alarm set mean monitor 30 seconds to sense all doors locked before setting or set first and cancel if a door is open 30 seconds later?
I assume if my door is open, keys in hand and I lock with door switch, the alarm should be set. (except the door is still open) I assume I have 30 seconds to close the door before alarm actually sets.

 

[Retiredad]

 

[Retiredad]

Do you get horn and lights when it's triggered by ghost or thief?
Is it still in NO START condition?
When it's start able, try starting in R, D, 2,and 1 to test PNP.
There are 4 physical shapes of the relays. No 2 are the same physically or circuitry.
Only one will fit physically. Only one will match your diagram. I'd get a new one that fits physically.
If that doesn't work to enable/disable alarm, I'd look at disabling.
The 30 second delay is internal in the SECU. Can't touch this.

 

[Retiredad]

Thanks for the 2004 manual. Amazing how different it is from 2000.
Arming and disarming are very similar. Features and circuitry are much different.
Your relay appears to be 2M Brown. Named Vehicle Security Lamp Relay.
2000 has a separate relay for the interrupt. 2004 is interrupted in the SECU?

When the vehicle security system is triggered, ground is supplied intermittently
● to vehicle security lamp relay terminal 1
● to horn relay terminal 1
● through smart entrance control unit terminals 39 and 42.

 

[Retiredad]

Relay slot was empty and the door was first closed, the Security light was off. When I opened the door to pop the hood, the security light came on and I started counting.

2000:
Disarmed phase The theft warning system is in the disarmed phase when any door(s) or hood is opened. The security indicator lamp blinks every second

I'm guessing, this occurs through the door open sensors, relay is not involved.
Note it's a1 second flash. Indicating disarmed. Note: It should start in this condition. (with a working relay installed)

 

[Retiredad]

I opened the door and got inside. Still flashing. It did not stop flashing until I attempted to start the truck, which did still go click click click with the starter and nothing more.

2000:
4. Activating the Alarm Operation of the Theft Warning System Make sure the system is in the armed phase. (The security indicator lamp blinks every 2.6 seconds.)
When the following operation 1) or 2) is performed, the horn, theft warning horn and headlamps operate intermittently for about 2.5 minutes.
(At the same time, the system disconnects the starting system circuit.)
1) Engine hood or any door is opened before unlocking door with key or multi-remote controller.
2) Door is unlocked without using key or multi-remote controller (applies to early production models).

Did you close the door when you got in to start it?
Did you notice if it was flashing every 2.5 seconds? I think not. It's only supposed to last 30 seconds @ 2.5 sec. I'm guessing that is still an open door signal. Remember, it should start if it's flashing every second. unless it's a bad relay.
I'm thinking you armed the interrupt when you plugged in a bad relay?
You triggered interrupt when key hit start position.
If you can repeat this, try unlocking door with key, relay in, before you try to start.

 

[Retiredad]

My opinion is avoid PNP (PITA). Except for testing. Does it work? Try R,D,2, and 1.
However, that won't test if relay or (in the 2004) SECU is faulty.
We haven't got into the interrupt circuit yet. 2000 is clearly in a separate relay.
2004 appears to be internal in the SECU.
Another fear is that jumping relays could have sent a surge or short into SECU.
It appears your relay is at least partly working. (It's a lamp relay, so the lights should come on)

 

[Retiredad]

2004:
VEHICLE SECURITY SYSTEM DEACTIVATION
To deactivate the vehicle security system, a door must be unlocked with the key or keyfob.
When the key is used to unlock the door, smart entrance control unit terminal 10 receives a ground signal

(I'm assuming you are not getting this signal)
(One idea is to force that signal) (use key to unlock door)
(Caution, I think it should be a 5 volt signal, not 12?)
(The point is to get system into a start condition, then look at disabling)
(see page 54 for SECU terminal 10)

● through front door key cylinder switch LH terminal 3
● through front door key cylinder switch LH terminal 2
● through body grounds M14 and M68 or
● through back door key cylinder switch terminal 3
● through back door key cylinder switch terminal 2
● through body grounds D402 and D404.

When the smart entrance control unit receives this signal or an unlock signal from keyfob, the vehicle security system is deactivated. (Disarmed phase)

 

[Retiredad]

After reading further into 2004 ... There is troubleshooting and system checks.
Your trouble is symptom 5 ... since we don't have a keyfob, only thing to check is key cylinder switch or body grounds.
I watched a video where a tech found a wire in a rusty area that looked fine and only revealed corrosion weakness inside by tugging on wire and it broke. There was also a clearly visible badly corroded body ground in the same area.
They were suspecting a bad module ($1000) and ground repairs eliminated the problem.

 

[Retiredad]

There are tests listed for every pin on the SECU and the multiple related connections. These are static tests of voltage or continuity. Sadly, none of that tests the logic inside. That requires live under load operational tests of same said connections.
Rock meets hard place. Focus on disarming interrupt.

 

[Retiredad]

Good point to revert to KISS.
My experience of the interrupt was not continuous clicking. (like low voltage on a relay)
I heard a new click every start try, (no clicking from start relay?) coming from TWR location. (made sense to me)
I've been focused on the TWR for my own reasons and assume starter system always worked. It's certainly possible that a start circuit or voltage loss fault has recently appeared.

 

[Retiredad]

the N&P/Clutch Interlock Relay. It turns out, N&P stands for Neutral and Park. That is the PNP Relay.

Interesting, to say the least. That is not in the diagram we were working with. When I was troubleshooting mine, I had to go to the AT manual to find the diagram for SC starter cutout. That did include a switch for PNP and one switch for clutch. I don't recall a separate relay for that. I looked at the access to PNP and the mechanics inside and ran the other way. (TWR)

I have no idea how to replace the female part of a Relay.

I don't know what that would be. I imagine the relay having prongs (male) on the bottom.
I imagine the fuse block being the slots (female) that prongs plug into.
I'm thinking there's no need to clean a bad relay but yes to cleaning contacts in the fuse block (with batt disconnected) with emery board or nail file. ( or tiny wire brush)

1 Charge battery
2 Replace relay
3 Key unlock doors
4 Park or Neutral
5 START?

 

[Retiredad]

I couldn't attempt to answer your question without the right diagram. IF I found the right one, we can move forward. This is from the 2004 Start/Charge manual (SC) on the page listed for A/T. (automatic) PNP relay indicated by mouse arrow.

 

[Retiredad]

dad thinks that crossing 5 and 7 and then attempting to key start the truck should start it.

I disagree. Jumping 5 to 7 would send start signal (12V+) from key start to whatever circuit to the left. (EC-PNP/SW).
To defeat the PNP you could jump 5 to 3 (hot wired start, always hot through PNP) or deny power (disable) to coil at terminal 2. (never powered, never interrupt, UNSAFE allowing start in gear)

To answer your original question, to disable TWR (VSR vehicle security relay), you could deny ground signal coming from TWR terminal 4.(allowing PNP to function and never trigger interrupt with TWR)

If the diagram is correct and I now believe it is, I think it's time for a Mic drop 🎤

 

[Retiredad]

Should I Not be getting 12 volts at the coil (PIN 2) in the PNP Relay when it is in the ON position?

First assumption: Key is in ON position, not PNP relay in ON position.
Second assumption: Negative probe of meter is connected to ground. Positive probe of meter is connected to "female side of relay" (I assume that means the open socket in fuse block when relay is removed)
Third assumption: PNP switch is working properly in park or neutral.
Fourth assumption: We are using the same, correct diagram?
Fifth assumption: A screwdriver across the terminals of starter with key on, will test starter.

More info needed.
First question: Is second and fourth assumption true?
If all are true, yes, there should be 12V potential between term 2 and ground. This does not verify any questions about relay or disabling interrupt. It would verify the key on through PNP switch circuit.