Not my Q but a contact's Q.... Basically what happened is the car ran great to the grocery store and then refused to start... I recommended to him to replace the starter relay and no go. Im waiting on confirmaiton from him to be sure its the security system and im reasonably sure it is, which is why im taking the next step.

ive been doing some reading in the FSM and previous posts and Im going to try and iron this down for him, in case I drive down there and help him out.

Heres the wiring diagram...



IN question is "theft relay #2" which is the black relay behind the ECU... If Im reading this correctly, the relay is normally closed but the BCU can (via the "top" pin) can open the circuit which prevents +12volts to get to the starter relay.... If I wanted to bypass it, what would I be doing?? I assume id leave the relay intact and i guess just cut the wires to those 2 pins which keep the relay closed or open and install a switch there, right? Or possibly install another relay where it would always be "normally closed"?

your asumption seems to be correct in theory, but theres only one way to find out!

If you know where the starter relay is just pull it and jump the two contacts with a jumper wire. If it starts the problem is in the ignition switch, inhibitor switch, or the theft warning relay or related systems. If it still doesn't start there is a problem with the starter, 30A fuse, or the fusible link.

Obviously there are a few other possible issues but those items are pretty easy to troubleshoot and should get the problem narrowed down.

So are you thinking that I can just geta length of thin wire and jump that and be all good??? May need to do the theft system relay too...???

I would assume if the security system isnt acting up (light blinking when it shouldnt be) it wouldnt act up like this....?

According to this wiring diagram it looks like the theft system relay has to be closed in order to even get power to the starter relay, so would closing the starter relay power circuit really do anything?

Basically what this Q was doing: He left it in the grocery store parking lot, came back out and it wouldnt do anything. Full battery good alternator etc.. Apparently the security light wasnt blinking he indicated to me it was normal (I told him what was normal)... Left the car there overnight and came back and it started He then went to the bank and turned the car off (stupid) and it did the same thing....

What would you think it would be? You thinking maybe a bad ignition switch?

I'd be leaning toward a bad starter solenoid, seen that dozens of times (not on my Q, just cars in general). If the car wasn't so low you could climb under there and give it a couple good wacks with a hammer when it was acting up.

The power to the starter relay's coil does pass through the theft relay but the actual starter wires don't. You'd want to jump the two wires labeled E3 at the starter relay and if the starters good, the 30A fuse is good, the inhibitor (neutral safety) switch is ok, and the fusible link is good it should crank right up, even if the key isn't on the starter would spin.

I doubt it's the theft system like you said, unless it's just a bad theft relay.

Here's a diagram showing the path of the power for the starter so you can see if you jump the E3 terminals it should crank if the path is clear, meaning no blown fuses, etc.

Ok, I was trying to make a slightly more permanent fix... I see where your going with that though... I know people have jumped things before when the theft system gives fits and badspells...

It isa bit more common that theft system immobilizes the car than a bad starter or solenoid, normally we dont see that on Q...

I was trying to make some sort of "patch", and I suppose this would be one way of "hotwiring" the car, because in theory if you could get the ECU to power up and jump these wires it should start... I guess as a temporary fix you could wire a start switch... If it acts up flip the key on open the hood and press the button...

also correct me if im wrong, but when the ignition is on, you should be getting battery voltage at connector E4... If your not getting 12v there you have some other relay problem. If you are getting 12v ubt its still not going, something is causing the starter relay not to fire... Jumping E3 shoudl force the starter to go. If it goes then, you probably have a bad inhibitor switch or a bad ignition switch. if the starter doesnt go then, you either havea bad solenoid or starter (which I dont think you can replace the solenoid seperately).

My instruction was just to aid in troubleshooting the problem. If jumping E3 makes it crank then the problem is before the starter relay (or maybe the coil of the starter relay), which would be the theft relay or system, the ignition switch, or the 10A fuse shown. If it still doesn't start/crank then the problem is after the starter relay or the main power to it. Fusible link, 30A fuse, inhibit switch, or starter/solenoid.

At E4 you should always have a ground on the ground lead (B) and on the other lead (B/Y) you will only have 12V+ when the key is in the crank position, assuming the theft relay isn't cutting your power. If you want to rule out the theft system you'd want to jump wires B/Y to G/B at the theft relay so it couldn't cut out the starter relay.

im just thinking in ease of accessibility.... The theft relay is kinda hard to get to (have to take the ECU out) whereas the starter relay is right there... Takes 5 mins to get the starter relay out and get your VOM all ready to go... I went out to try it on mine and my VOM kicked the bucket .. 2 years of service $20 from walmart, not bad I think... Kinda hard to do tests when the positive wire on the VOM falls out of the probe!

I really hope Im not being dense here, im just trying to get an idea on whats going on... I can do the hard stuff but when it comes to simple stuff it throws me for tailspins sometimes....

I really hope this helps someone out sometime, and Ill porbably move this to the online mechanic (where it should be now anyway)....

So to sum this up for the electrically challenged.. This is all done at the starter relay. I really think the more I anaylze this the more confused Im making myself...

1. Testing at connector E4 should give you 12v when the switch is in the crank position... If it doesnt, you either have a bad ignition switch, theft relay, or inhibitor switch.

I suppose you could also skip to just to jumping E3 and see what it does, that would tell you if you have 12volts... If I understand correctly jumping this connector E3 and leaving E4 connected should make the car crank regardless... If it does, then you have the bad ignition switch, theft relay, or inhibitor switch........

however you could have a bad or open theft relay and it still wouldnt crank even jumping E3, right?

2. If you have 12volts, reconnect that connector E4 to the relay... Jumping this connector E3 should make the vehicle crank... If it doesnt then you have a bad starter....

3. If the starter still doesnt go after doing (2) then you have a bad starter or the starter relay coil itself is shot.

Ok...

#1. Correct EXCEPT, might also have a failed 10A fuse (shown top middle of your diagram on right side of the fuse box). Also, NOT the inhibit switch. The inhibit switch is in the loop from E3.

Yes, jumping E3 and leaving E4 the car should crank regardless of ignition switch position or anything else. As long as your battery has power, hehe. If it does crank...yes, bad ignition switch, theft relay or system, or 10A fuse. NOT inhibitor switch as explained above.

The theft relay is completly irrelevant if you jump E3 as the theft relay only interrupts the coil side of the starter relay (E4), not the switch side (E3). So if you jump E3 it will crank if the theft relay is telling it not to.

After going through all this, probably one of the first things I'd do is test for 12V+ when you turn the key to the crank position at several points. First, directly at the ignition switch starter wire (Black/Red I believe). If you don't have it there check the ignition switch and main fuses under the hood. If you have power there, check that the starter relay "clicks" when you turn key to the crank position. If it does but the car doesn't crank check for constant 12V+ on the W/B wire at E3 (White/Black I assume) if you don't have power there check the 30A fuse shown at the top middle of your diagram and the fusible link.

If you did have power on the W/B wire but still no cranking check for 12V+ on the B/R ( I assume this is black/red) wire at E3 at the starter relay while you turn the key to the crank position. If you don't have 12V+ then you have a bad starter relay. If you do then you must follow the path through the inhibitor switch then to the starter to see where it stops.

I usually start at the source (ignition switch) and follow the path to find out where it stops. Now if his problem is intermittant it's not going to be a fuse. Could be a relay going out or I'd seriously look at the starter/solenoid. Solenoid problems are very often intermittant like that.

Hope I didn't confuse you more. hehe

elwesso wrote:
Basically what this Q was doing: He left it in the grocery store parking lot, came back out and it wouldnt do anything. Full battery good alternator etc.. Apparently the security light wasnt blinking he indicated to me it was normal (I told him what was normal)... Left the car there overnight and came back and it started He then went to the bank and turned the car off (stupid) and it did the same thing....What would you think it would be?

I've had these same symptoms except for the security light (can't say as I looked at it). He should take a look at the battery connections. My OEM positive clamp wouldn't tighten properly and I didn't replace it until after I'd replaced the starter relay (1st) and then the starter (2nd). When I took it to the shop after the problem came back the mechanic pointed out my marginal clamp and replaced it. Too bad because I returned a perfectly good OEM starter for the core deposit.

Wes- Is he still getting power inside the car, all except the starter? Don't throw money at parts like I did. Have him check the battery connections. I hate chasing electrical gremlins. Good luck.

Thats sort of what I was thinking... he said he had good power to the car.... Said the connector may have seemed loose... I assume Ill be hearing back from him in the next few days...

BTW shane im still digesting your post... I totally dig what your saying im not sure why im being so dense about it, ive solved much worse electrical gremlins on my Q (cruise control-- EWW)

So what was the final out come of this fix????? what was it and how did you fix it

thats right

I am lost in how to fix my 1998 Q45. The theft alarms go off when I unlock the doors. My fob no longer works so I use my key to unlock the vehicle. This unlocking triggers the alarm and nothing I do can stop the alarm except pulling the battery cable off. Can anyone give me advice?

Hi Ron!

Welcome aboard. I'm thinking it might be a good idea to start that as a new topic. Meanwhile, I'll check with our resident electronics experts and see if they have any helpful suggestions!

Try this process, but also order yourself a new fob (they're cheap on ebay):

Step 1
Insert the ignition key into any door or the trunk lid and unlock the door or trunk. You also can use the unlock button on the remote control to unlock any door or the trunk. This will silence the alarm.

Step 2
Get in the car and insert the ignition key into the ignition, but do not start the car.

Step 3
Remove the ignition key from the ignition.

Step 4
Exit the car and lock the doors using either the ignition key or remote control.

Verify that the security indicator light on the dash illuminates. The security light will glow for about 30 seconds and then blink. The security system is now reset.

If you get to the point of having the system disarmed, I've been told by an alarm installer that either disconnecting the hood pin switch - or leaving it connected and unbolting and leaving the switch dangling under the hood (I can't remember which one) will fool the security system in to not arming. This was for an older Q, so it may not apply to your version.

I have tried all suggestions without success. Locking and unlocking doors did work a while back when this started happening but now nothing stops the alarm until time expires on the system alarm. Problem is once it stops it starts up again every time I do anything with the locks. I did remove the hood pin and thought that might do it since the rubber cover for the pin had worn off as the pin was extended all the way when hood is open. Does anybody else have any ideas? Thanks for suggestions and will check eBay for fob. Good idea. I have to lock my doors because the car stays outside and you can get into my garage and home with garage door opener that’s programed in my he car.

Key fobs are cheap, just make sure that you match the coding. Not sure about your model, but the G50 were able to code their own key fob by opening the truck and following a few steps from the FSM. I picked a decent one for less than $15 shipped. I added the link for the item on ebay

https://www.ebay.com/itm/Upgraded-Remot ... 2749.l2649

Thanks but my Q45 is a 1998 and this fob is for older ones as you mentioned might be the case. I have the car back from Electrican and he said he shorted out the hood sensor and thinks it might work. So far it is but now my horn doesn’t work at all. On top of that my power steering went out this past weekend. I think G-d is trying to tell me something...to junk this car. It hurts to do so because the engine and body are still in good shape.

The 1998 Q45 key fob must have different inside components than the 89-96 Q45, because the key fob shell looks the same. That NATS system is one that I'm not familiar with, since I have the system before and have had the system after (2003 M45). The M45 had the system where the key fob was also the ignition key, with a emergency hide a key inside the key fob. It cost almost $500 for a replacement, from Infiniti. I don't blame you for considering letting go of the car. Lot of folks have given up trying to maintain their Q45, especially the 1st gen. I'm not sure how much longer ill be able to maintain mine, now that Infiniti has discontinued parts for it.