Hi guys,

I'm needing some direction regarding my Q45. It's been literally neglected for the last 9 years as far as driving is concerned.

It started out when the engine just stopped when warming up. This proceeded to Pig Rooting when accelerating. (massive jerking)
Then the ABS seems to be sticking on the Rear brakes only, and finally, it won't leave 2nd gear. The transmission seems to be under strain when in forward gears. It sounds like the pump is working hard. (can hear it like a Power Steering Pump under load.

Normally I'm set in fixing these problems, but none of my Scan Tools will now read the Engine, Transmission or the BCM. It can read the ABS and the IVMS and do all the activations etc.
All the Fuses are OK. All the connections have been checked. All the Control Modules have been checked for any signs of "Burn Out" and the circuit boards seem perfect.

My main question, is this indicative of one area playing up (eg BCM) or is there something simple like a faulty relay I should check first.

Any help would be appreciated.

Cheers

Probly compromized / corroded contactcs in X number of your relays , the ELECTRICITY IS DOING THE JERKING ? Making the mechanical stuff jerk too

Circlejerk around - check 'm all .

The engine seemed to be cutting out and turning back on, to the point it was spinning the wheels. Too sudden to be fuel. Will be checking all the circuits one by one, but would love it if someone has had a similar issue, even one of the symptons and fixed it, just as a starting point.

I'm still leaning towards the BCM, as it's the common connection to many of the problems.

Chally wrote: ↑

Mon Jan 24, 2022 5:12 am

The engine seemed to be cutting out and turning back on, to the point it was spinning the wheels. Too sudden to be fuel. Will be checking all the circuits one by one, but would love it if someone has had a similar issue, even one of the symptons and fixed it, just as a starting point.

I'm still leaning towards the BCM, as it's the common connection to many of the problems.

BCM--you mean the Body Control Module? Unlikely. That thing is for creature comfort type stuff.
sticking rear calipers could be a lot of things mostly mechanical--but do you get a solid buzz-thunk (ABS self check) when moving from 0 to 5-ish kph on initial start-up? Don't forget there are ABS relays (near firewall--generic black Japanese ones, NOT nissan branded) that can preclude proper ABS and keep pressure on the rear calipers).
the tranny whine/groan is usually low fluid.
have you measured the fuel pressure yet? come to think of it--that gas can't be anything usable after 9 years?

PS welcome back

The brakes release when you open the bleeder. It is holding pressure after the ABS. No abnormal noises, and come to think about it, the "Test" thunk has been missing for a while. Are the relays under the plastic cover on the ABS unit or seperate from the unit on the firewall?
The fuel isn't that old, I have kept driving it occasionally, just not very much. eg 1000km a year. Fuel is fine. Pressure? Doesn't seem to exhibit "low pressure" actions, but I'll check it out.
Transmission fluid is the correct level. Low fluid would cause a lack of drive. When I went for a drive, it changed gears lovely. An hour or 2 later, the gear was stuck in 2nd only. Would do reverse OK, but in forward, only 2nd. Something is putting it in a Limp Home mode and making the Transmission pump to overwork... The whirring is not loud, but has the sound you get when you pull the Kickdown Cable on the transmissions that have them. More testing... Pretty sure it's electrical
Thanks for the suggestions

If your testing statically , not driving around - great . But I would change transmission fluid AND a FULL brake bleed or flush , proper and thorough , and see where you are then . Sketchy to drive too much , too far.
Brake fluid in ABS probly ' soup ' , transmission - your just circulating 9++ years of crap throughout the valve bodies passages ??

Agree on the Brake fluid, but the Tranny fluid is still like new. Not even dis-coloured. Built the box myself and used Caltex (Texaco?) fully synthetic fluid. It should be good for for at least double the miles yet. Could be a sticky valve, so I might just change it to be sure.

a vacuum test and fuel pressure test are what I can recommend

vacuum test?

Fuel pressure won't make the gearbox select the wrong gear. You can still spin the wheels on grass in the "Locked up" problem, so there's enough fuel being delivered.

Feels like its selecting 2 gears. It rolls easily in reverse, but just about locks up in drive... I'll be changing the oil & filter (gearbox) as soon as my hoist is free. I'll post the results.

Is there any of the old experts still around?

Here is a list of the problems again:
1. Entry Key not working
2. Can't access the Engine Diagnostics with scan tool
3. Cant access the Gearbox Diagnostics with scan tool
4. Can't access the BCM Diagnostics with scan tool (could always access it previously)
5. "Steering wheel up/seat position back" for easy exit only works after removing & inserting the key twice.
6. Gearbox stuck in 2nd gear & feels it may be holding onto another gear as well (only in 1,2,3,D)
7. Air Cond. stopped working (still has gas)

All these problems surfaced almost together making me feel there is a d!ck "Relay" causing voltage feed drop somewhere.

Thanks to everyone's suggestions. I really do appreciate it.

Electronic issues, begin at the source, the battery and a load test. Weak cell(s) will show their gnarly head at the most inopportune times. Then move to the ground circuit connections. Cleaning and re-attaching. What else ?

I don't know about your specific harness, but if your picking up ground connectios all over the place, this could equal electronic issues. Hang in there

Thanks mate. I'm betting on a broken(chewed) wire or harness somewhere. Progress is slow due to many other jobs that have more importance.

Have you tried running the self diagnostic procedure on the ECU. If you read/download the EC chapter of the FSM, it contains the self-test and diagnostic procedure. Since your car is pre-OBD2, you will have to follow the self-test functions or get a Nissan CONSULT adapter. It's basically just a RS-232 to USB adapter. Go to Nissan Datascan website, and look up their Datascan 2 program for the Q45.

I'll give that a go. I have the Nissan workshop manual. Most tests I've done so far have failed. Occasionally the scan tool will sense the module, then promptly lose it. I'll try doing some manual self tests to see if that leads somewhere.

Thanks

Do you get "OK" or any malfunction message on the dashboard display lower right side, after starting or trying to start? If don't have any msg, then do a bulb check, by turning the selector screw CW on ECU. It should test warning lamps and the display.

If you do get an "OK" then I would then check fuel system and all your fuses and CB.

All the message lights are OK. Most tests I have done come back as Faults. I have to take the inner guard off to check the wiring under there. I'm not sure there may be a mouse or rat living in there. The dog was very interested in that area for hours, not long ago, but getting the time to check it has been an issue. That is where the main wiring enters the cabin, from next to the air box.
I'll share what I find.