Wiring

[RichZilla]

Can you hear your injectors pulsing while cranking? If not, then your spark issue is a crank angle sensor problem.

It not something stupid like the coil earth wires not screwed in? (near the front coil on each bank)

[zehnder]

Thanks for the reply,The earth(ground) wire is hooked up to the front of head where it screws in near #2 cylinder.I was unaware that to receive spark at coils the fuel injectors must be operating as well. I must confess I didn`t check to see if they were clicking while cranking as I was doing this without help.I`ll have to get someone to turn key while I listen.As far as crank angle sensor,engine ran decent before I did the swap (even with #6 injector not at 100%)and I sure didn`t mess with this sensor. If I`m not getting a voltage at crank sensor, would this be my problem?Ecu is supposed to supply all sensors through harness,right?All my harness wires are hooked up but maybe I should check continuity of sensor wires.

[zehnder]

I`m still wondering if one of our resident experts are still contemplating on doing a detailed electrical write-up on basic engine start-up for the VH. The issue could be settled once and for all in a "STUCK" thread that would contain , step by step, using a stock ECU , relays and engine harness. The factory manual has tons of good information on this subject but, to me at least, feels a bit intimidating since it includes all the systems from the donor car. The help i`ve gotten from this site has been very informative, although in a somewhat disjointed fashion. I understand that the wiring may be slightly different due to yr of engine but the ECU is the same, Right?

[tmorgan4]

I'm pretty confident that I've got mine wired up 100% as the entire harness is almost built. I'm just hesitant to write up how I did everything and have major problems the first time I try to start it.

[T45]

I haven't started yet. I am gonna try and drop the engine in this weekend and get mounts welded up. It should only be about 10 wires or so that need to be hooked up.

[RichZilla]

Ahhh to be using a manual trans.. That's about sixty wires less than what I had to connect up.

[T45]

Yeah I had originally planned on putting the auto and VH into my truck but sold the truck and got a Z32.

When I stripped the q's harness it ended up about 25 feet long and probably 40 lbs of wires not including all the relays and modules and computers.

So after I got the Z I was able to chop about 30 lbs and a billion man hours off the harness!

[T45]

Hey Morgan, got any diagrams finished yet? I just started looking at FSM's today and am having a hard time.

The 300ZX FSM I downloaded is incomplete and the Q diagram is contaminated with gianormous migranes.

EDIT: I just re-read this thread and put together some of the Q wiring. I'll see if I can figure the rest out.
Modified by T45 at 7:35 PM 12/1/2007

[tmorgan4]

I've got some diagrams partially done for the wiring harness I made, but I'm just now getting a chance to test how well I thought things out. I made a few minor changes today but everything seems to be working good. I haven't gotten the engine running because I'm having wiring problems...but I'm thinking they are all pointing back to a bad ECU. I just really want to make sure my wiring is correct and works before I give out too many diagrams.

[T45]

No sweat, I still need to figure out the Z half of the wiring too.

[tmorgan4]

I was actually wondering about that....I wonder how similar the VG33 wiring is to your VG30. It would be great if they kept it at least somewhat similar.

[T45]

I have a few quick q's about the VH ECU wiring.

The ECU has 2 FPCU wires coming out, IIRC they are pink/blue and green/orange. The Z only has one wire for the FPCU. Is there a difference between the 2 and which one to use?

The FSM also lists the ecu as having 2 wires that control the cooling fans but mine has none. IIRC they are pins 4 and 5 on the ECU harness. What is everyone else doing to control the fans, adding in a switch or aftermarket fan t-stat?

Lastly is the inhibitor switch wire. Is this ok to leave disconnected or does the ECU need this wire grounded for proper operation?

[tmorgan4]

Are you sure that your fuel pump controller only has one wire going to it? I see that in one of the diagrams it only shows a single wire + separate (non-ECU) ground, but in the actual circuit diagram (EC Page 12) it shows 2 wires. Check ECU terminals 35 and 104 as those are the two listed.

I'd be interested to hear back about the inhibitor switch as well. Mine is not connected to anything yet. I was also curious if the neutral position switch matters in a 5-speed. My guess is NO.

[tmorgan4]

It looks like both the 300ZX and the Q45 both use only a single varied voltage wire to the fuel pump controller.

Check these pages: 300zx EC Page 24

Q45 EC Page 25

If you compare the specs you'll see that the fuel pump controller out of the TT 300Z is a lot closer match as far as voltages go, but since you've got the whole vehicle I'd just swap in the Q45 fuel pump controller since you're probably going to upgrade the pump as well, right?

I have read that quite a few people just bypass the fuel pump controller all together so it always runs on 12V (or battery voltage). FYI, my Pathfinder doesn't run a fuel pump controller. It's on/off via the fuel pump relay and I'll be keeping this setup with the Walbro pump.

[T45]

Yeah I guess there is a difference between the NA 2+2 and the TT 2+0 or something. Either that or the fact that it's a 90 vs. the 94 FSM. The brown connector that shows a black/purple and purple wires is missing the purple wire on both sides of the connector and it's plugged up as well. There never was a purple wire there so the FPCU only has one control wire. I was just wondering if there was a difference between the 2 FPCU wires on the VH ECU. Hopefully they have the same function at WOT.

I believe the 5 speed neutral is just to adjust timing and possibly the rev limiter in neutral so you don't blow the engine revving it freely.

I also found how the fan is controlled in the Q. It comes on with the a/c via the relay but also there is a thermoswitch in the Q radiator that apparently grounds the fan relay when the temp gets hot. I need to go and take a look at it and see if I can fit it in the Z radiator or integrate it somehow.

Thanks for the help!

[T45]

I am going to swap the Q fuel pump in but was just going to swap the pump itself. I may just bypass the FPCU like you said. There is really no harm in running it at full pressure all the time as the regulator will adjust accordingly.

Great, more re-wiring. lol It's not that tough it's just really time consuming with small headaches placed throughout my day.

[T45]

I checked those voltages and they seem like they will be ok. According to the voltages it should operate the pump with just a little more pressure at cruising speeds and full pressure at WOT. Nothing wrong with that.

[qsiguy]

IIRC, the older pre '94 Q45 fan is controlled by a thermostat and the newer, '94-95 Q45 uses the ECU to control one of the cooling fans. The A/C fan comes on with the A/C.

The FPCU will just increase the life of your fuel pump. If you don't mind running it at full speed all the time it's not needed.

[T45]

Thanks for the info. I have it wired up and am going to put in a small inline fuel pressure gauge. If it works like it's supposed to then great. If it doesn't then I'll just wire it up in ludicrous speed.

[slamdbusa]

Be sure that you don't go PLAD.

[T45]