280z Fuel Injection Harness Differences

[pakmule87]

Hey guys, I am working on a side hobby of rebuilding old fuel injection harnesses and nearly have one done, but was wondering what are the differences (besides how some have spliced the Thermotime Switch and Cold Start Valve together, have a 2/75 harness that butt connectored them, and an unknown that I have about done that tied them in at the Cold Start connectors) between year models are?

[FastWoman]

I suspect very little. There were differences between years in how the fuel pump shutoff was handled. In earlier years, there was a switch in the AFM that required 2 more wires than in later models. The connectors are the same, just having non-connected or missing contacts in later models.

[Wade Nelson]

Isn't your post rather like Einstein asking the guys he rode the bus with about relativity? You're the expert, man! Have you drawn any schematics?

My goal is STILL to see why the ECM is tied into the cold start valve, whether to monitor it, or to "cheat" and use it for additional enrichment under acceleration or something. Gonna put a data logger on it or a dash light to watch that signal under a variety of conditions.

Help me here, I'm away from my FSM and blown-up schematics, one side of each injector goes to the ECM for grounding (to squirt) , does the other side go to the relay behind an access panel (near the battery) to provide 12V when the relay is energized? I'm still having a (bitter cold) cold start problem where the injectors are not firing. I suspect dirty contacts on that relay.

Cheers!

[rcb280z]

Here are some numbers you can look up 24011-N4700 , -N4701, -N7700. Got these from my microfiche. Hope it helps.

[Captain Obvious]

My goal is STILL to see why the ECM is tied into the cold start valve, whether to monitor it, or to "cheat" and use it for additional enrichment under acceleration or something.

Wade, Don't know about your ZX, but on the Z The cold start valve is not tied into the ECU.

I believe you are referring to the mysterious "pin 21", and if that's the case, then remember that while there is a wire going from the cold start valve to the ECU connector, that signal does not actually make it inside the ECU case. That pin location is not populated. No pin at all, just a blank hole. That signal makes it to the ECU connector, but it doesn't go any farther than that.

Would be interesting for you to take a look at your ECU and find out if your ZX populates that pin location. Maybe they started using it in later years? :bulb:

[pakmule87]

My goal is STILL to see why the ECM is tied into the cold start valve, whether to monitor it, or to "cheat" and use it for additional enrichment under acceleration or something. Gonna put a data logger on it or a dash light to watch that signal under a variety of conditions.

Help me here, I'm away from my FSM and blown-up schematics, one side of each injector goes to the ECM for grounding (to squirt) , does the other side go to the relay behind an access panel (near the battery) to provide 12V when the relay is energized? I'm still having a (bitter cold) cold start problem where the injectors are not firing. I suspect dirty contacts on that relay.

Cheers!

The other side of the injectors come off of the resistors next to the master cylinders giving the power from the battery with the only connection being at the resistors. At most (I speak from not much experience, so somebody feel free to correct me if I'm speaking from stupidity) from the cold start valve is to put more fuel to the engine when it is as you can assume cold, and can cause it to flood (or require a tune up as Nissan mechanics will falsely tell you back in the day) if your temp sensor has something wrong with it or the connection.

I will be going through all the FSMs when I get the chance to check, was just trying to be sure if there was possibly something left out or missed, since so far I have been going off of the 76 (since that is the model I have and no since having 4 manuals on my phone when 1 will do) and it has matched up. But whenever I do get it done and on eBay, the old "check to be sure" should cover any problems other than idiots with only one choice of negative feedback since eBay probably wont help them

[Captain Obvious]

The other side of the injectors come off of the resistors next to the master cylinders giving the power from the battery with the only connection being at the resistors. At most (I speak from not much experience, so somebody feel free to correct me if I'm speaking from stupidity) from the cold start valve is to put more fuel to the engine when it is as you can assume cold, and can cause it to flood (or require a tune up as Nissan mechanics will falsely tell you back in the day) if your temp sensor has something wrong with it or the connection.

I will be going through all the FSMs when I get the chance to check, was just trying to be sure if there was possibly something left out or missed, since so far I have been going off of the 76 (since that is the model I have and no since having 4 manuals on my phone when 1 will do) and it has matched up. But whenever I do get it done and on eBay, the old "check to be sure" should cover any problems other than idiots with only one choice of negative feedback since eBay probably wont help them

I can't even figure out what you're trying to say. What does ebay have to do with anything?

There's a guy on HybridZ (FricFrac or something like that) who does a lot of work with the FI harnesses. Why don't you just buy one from him? I think he offers everything from connector "kits" to turn-key harnesses.

S30 and S130 Wiring Harness repair kits. You NEED this if you have an L28E or L28ET! - Parts for Sale - HybridZ

And I believe he does have some of his stuff on ebay... Is that what you're talking about?

Are you saying that you're planning to actually SELL rebuilt harnesses on ebay? If so, that's not a "hobby", that's a "business".

[pakmule87]

Then we will consider it business then.

And I will be buying from Fricfrac for connectors. What I am doing is redoing the heatshrink, and replacing all the terminals for fresh connections for all ends as well for these with just reusing the connector housings that I haven't been able to find and the wiring from the old harness.

Edited March 28, 2013 by pakmule87

[pakmule87]

Just finally got a chance to look over the FSMs for the 280z. 75-76 harnesses are made the same, the 77 harness adds in the altitude switch, with the 78 changed the relays,has the altitude switch, and cut out wires 39 and 36 from the AFM. Oh and Captainobvious, I didn't know Wade was talking about a ZX, so just consider me an idiot for that part of my ramblings and pretty much the rest of it too. A little bit of time actually looking into the FSM straightened me up on my...we will just go with complete idiot-ness

On a positive note, I think I figured out the only purpose of 21, which is checking continuity of the Cold Start and Thermotime Switch.

[Wade Nelson]

I think I figured out the only purpose of 21, which is checking continuity of the Cold Start and Thermotime Switch.

Ahh! I'll bet your right! I'll bet the Kent-Moore tester, which plugs into the ECM connector, is thereby able to check those items!

[Captain Obvious]

Here's what was suggested the last time we were talking about pin21:

So, about that pin 21? Why does the thermotime switch feed back to the ECU? I got two possibilities.

a) First is what Wayne mentioned in his thread... That Bosch wanted the ability for the ECU to activate the CSV instead of (or in addition to) a thermotime switch. If they would switch pin 21 to ground inside the ECU, it would activate the CSV while cranking. I don't remember what, if anything, that pin is connected to inside the ECU, but it may have been or a future enhancement.

Second theory is that it is simply a test point for being able to check the function of the thermotime switch. Seems Datsun wants you to do all of the diagnostic testing right there at the big ECU connector, and they provided that wire just to allow you to have the ability to measure the thermotime switch function. Without that connection, you would have no insight into the cold start system from the ECU connector.

Remember, I wasn't there when they designed the thing, but those are my guesses.

"a" isn't gonna happen without the ECU even making connection, so I'm sticking with "b".

[pakmule87]

I think its safe to go with B for the final answer. There is the possibilty of A, but the part that knocks that out is the idea of having the redundancy of the ECU controlling the CSV which would have to ignore the TMS or have the TMS tie into the ECU as well, but not the middle ground of how it does work and grounding to the ECU.