MAF Connector Wiring

[Amybirds]

I've searched the posts for answers to this question with no success, so I'll see if any of you can help (please?)...

My husband and I have a 1994 Q45. After a successful day replacing the bearings in the belt tensioners yesterday, we decided to go ahead and install the MAF connector kit we bought from Scottsdale.

We thought it would be a quick project to end our day with until -- oops! My better half realized he had cut off the connector without noting the position of the wires! We stayed up half the night trying every different combination of wire positions with less and less success. (First one seemed to work the best, but now when we try the same position, the car "dies").

Anyone know how to figure out the correct order of the wires to the MAF connector? Or have we shorted something out by trying the wrong order of the wires?? Or maybe just flooded the engine?

On a side note, anyone know if NAPA or elsewhere carries extra pins for the connector from Infiniti? (We soldered ours on too thickly and now they don't fit in the connector, even if we figure out the "right" order...) Thanks, Amy

PS: I'm posting this in online mechanic too in hopes some kind soul can help me out!

[maxnix]

Please limit posts to one forum. The moderators here are a little lazy in Forum discipline, so poster thoughtfulness increases relvance and decreases chaff.

In this case, Infiniti Online Mechanic Forum is the correct one and if you do a search for MAF connector, I think you will find a post that identifies the wiring for the connector.

Do you have the FSM and TSB?

And welcome to our club.

[maxnix]

Search for "MAF connector" in the body of text in this forum and you shall find.

And cross posting is a no no.

[Amybirds]

Sorry about the double posts and thanks for the welcome.

I have the FSM from the prior owner -- very dog-eared and missing many of the beginning and end pages (which very well may be the one I need as I couldn't find a page with the wiring diagram to the MAF). I don't have a TSB.

I've searched the posts and the best I can find about the order of the wiring can say is advice to note the position of the wires before you begin and advice not to mix up the wires. A little late for that now...

[Q45tech]

If you miswire and energize you have a medium to high probability of destroying the MAF............the +5V from ecu supplies power to circuits and the ground and the output +1.0-+4.4volts returning to ecu to report flow rate.

The +5volts to all sensors [TPS, coolant, MAF, CAS, and others] are generated buy one big IC regulator inside ecu......grounding this +5 can blow the regulator in ecu requiring a new ecu.

[elwesso]

Merged this thread with the thread in the Q45 forum, and cleaned it up.

[elwesso]

Also, here is the MAF wiring diagram!!!

[CrimsonQ]

If you miswire and energize you have a medium to high probability of destroying the MAF............the +5V from ecu supplies power to circuits and the ground and the output +1.0-+4.4volts returning to ecu to report flow rate.

The +5volts to all sensors [TPS, coolant, MAF, CAS, and others] are generated buy one big IC regulator inside ecu......grounding this +5 can blow the regulator in ecu requiring a new ecu.

I toasted a maf that way myself.

Not tryin to troll, but I have 2 Mafs on ebay now. You want one let e know and ill pull it off ebay.

[Amybirds]

We now have the MAF connector properly wired (thanks Wes!).

Unfortunately, we seem to have a new problem on our hands...

FIRST, last night while trying different wire combinations, the MAF wires sparked when starting the car. Both before and after this, the engine would start then die in every wiring combination we tried.

THEN... today, we inadventantly had left the keys in the ignition while trimming the wires to attach the connector which resulted in a spark/sizzle from the wires being cut and then a super rapid clicking noise from the engine compartment for a few seconds afterwards (in the vicinity of the canister control solenoid valve and the EGRC-solenoid valve).

NOW, when the key is turned to ON, there is a rhythmic clicking noise (about the speed of a turn signal clicking) from the ECU, also near/from the engine compartment near the EGRC solenoid valve, and also the fuel pump seems to mmm-mmm-mmm in time with the clicking too. At the same time with all the clicking, the engine light in the dash flickers, as does the LED on the ECU.

We tried pulling codes from the ECU and there were no codes at all. The light comes on and flickers in time with the clicking till we turn it clockwise and back and then it stays off till we pull the key out and try again.

When we try to start the car now, the starter does it's thing but the engine doesn't seem to fire.

So, how do I know if the ECU is fried (does the loud clicking noise give it away or could it be something else? ) And how do we know if we fried the MAF too?

Oh yah, we found that the "Engine Cont" fuse was blown in the engine fuse box-- we replaced it but the ECU still clicks away in the ON position and the engine won't turn over...

-Amy

[Q451990]

Wow... at this point I would say you have two options... start replacing modules and hope there aren't any wiring issues (melted, shorted, etc) - or have it towed in for some professional attention.

The ECU clicking doesn't sound familiar - but it's certainly not normal.

Heath

[elwesso]

Actually I bet i know what you did...

The MAF is wired directly into the ECU relay. As soon as the ECU relay kicks on it sends power to the ECU and the MAF... I would check the ECU relay and replace first.

[Amybirds]

This may be a very dumb question, but is the ECU relay the same as the fuse in the engine compartment? Because we already replaced that fuse and it didn't seem to make a difference.

Or is it what the FSM calls an ECCS Relay? If it's the ECCS relay, page EF & EC-79 in the FSM says it's behind the ECM but I looked behind the ECM and didn't see anything resembling this.

Or is it something else altogether and how would I locate it and check it out?

Many thanks!! -Amy

PS - I tried searching the forum for this with no luck...

[elwesso]

Amy

The ECCS relay is what your looking for.. You have to peel back that black foam, and then there a white plastic thing held in witha couple screws you need to remove, and then theres gonna be about 3-4 relays sitting back there.. It will show in the FSM which one you need to remove/replace.

[Amybirds]

Wow Wes, you are awesome! The clicking IS coming from the relay and not from the ECU itself! We'll try to acquire a new relay tomorrow if we can find a semi-local dealer that has one and try it out!

Keeping my fingers crossed, Amy

[Q45tech]

Relays click [go on and off] for a reason..............delve deeper and determine why the drive voltage goes on and off..............protective circuit breaker overload?

[elwesso]

What color is the ECU relay? Is it a blue relay..? If so, you can just pull another relay out from somewhere else and see if it works... According to the wiriing diagram, it looks like a standard blue relay with power thru pin 1/2 and normally open 3/5...

If thats the case, you can pull another relay out from elsewhere, like from the cruise control or something and at least see if that works.. its worth a shot..

I do agree with tech though, its gotta have an overload somewhere, but you should try and swap the relay with another one somewhere on the car first.

[Amybirds]

Well, we tried replacing the relay. It still clicks. The tick is in rhythm with a ticking from what appears to be the EGRC solenoid valve harness connector/area (looking at pg EF & EC-136).

The wiring diagrams I'm looking at don't show any shared wiring with the MAF connector & the EGRC solenoid valve connector or the ECU relay. Would the common denominator be the ECU? Is there a way to check the ECU to see if we damaged it before the fuse blew.

About troubleshooting the drive voltage -- where would I begin?

Thanks so much for your help! -Amy

[elwesso]

IM going to study the wiring diagrams and post up some thoughts later tonite or tomorrow morning.

[elwesso]

Alright i have looked over some of the wiring diagrams, and i think the first place you need to start is to look over the MAIN POWER SUPPLY AND GROUND CIRCUIT for the ECU... Do the diagnostic procedures in there..... i would HAVE to imagine it would be in there somewhere.....

All the diagnostic procedures dont look too bad, theres PLENTY of things to check and keep you busy.. fortunately all of them are fairly easy to get to (just probing the ECU).. If you are not familiar with probing the ECU and doing all of that fun stuff, let me know and I will help you guys out...

If this is you (Amy) doing all of this stuff to the car, I am fairly impressed with your prowess!! Maybe you will replace our most favorite and since deceased (assumed) Tangalora...

[Q451990]

Maybe you will replace our most favorite and since deceased (assumed) Tangalora...

http://profiles.yahoo.com/tangalora

[Amybirds]

Well, my husband does most of the work with the ratchet (and the wire cutters this time-- unfortunately), but he says I'm the brain of this operation.

I have some plans this morning, but when I come back I will find the section in the manual about probing the ECU. I will probably need your help with that -- I'll let you know after I read it over.

Thanks! :-)

PS: Tangalora seems like a neat person...

[Amybirds]

Ok, I did the ECM Inspection for everything that didn't require the engine to be running (which seemed to be most of it...).

Here's what I tested & the results:

Canister control solenoid valve: okIgnition switch: okPower souce for sensors: okPower supply: okThrottle position signal: .442 V (ok)Battery: ok

ECCS relay: ok when engine is off, but unable to test it with engine running, or just turned off from running. (noted that it was .888 volts when the ignition switch is "on", but the manual didn't give specs for that).

Inhibitor switch: ok in P, not able able to try N or other gears.

Fuel pump relay: ignition switch "on" (first 5 seconds): was 1.9V (ok) ignition switch "on" (after 5 seconds): should be 0V but instead it remained 1.9

Fuel pump voltage control: ignition switch "on" (first 5 seconds): was 1.9V (ok) ignition switch "on" (after 5 seconds): should be 0V but instead ut remained 1.9

Unfortunately, since I can't start the car, I can't test the items that I'd really like to know more about: MAF, EGRC solenoid valve, ECCS relay (with engine running)...

So, what I conclude is that the two fuel pump items that are supposed to stop getting a charge after about 5 seconds of turning it to "on" are still getting their "startup" voltage. Which I'm guessing means that something somewhere is not doing it's job of telling it to stop. Or the ECU is fried and not telling it to stop?

I checked for any sounds of relays clicking in the trunk/fuel pump area since the results above tell me there's something going wrong with the fuel pump electically: there are no clicking noises, but you can sort of hear the pump hmmm-hmmm-ing on and off in time with the clicking of the ECCS relay & EGRC valve, and there is a faint liquid-running sound that is also (even fainter) in the engine compartment when the key is turned to "on".

Now what. Should I test the EGRC solenoid valve? The page in the manual says to check for air passage continuity. What does that mean? Like, feel for air coming through? And when they show to run a line with a fuse from the battery to the item, I'm assuming that fuse-wire is something I can acquire at Radio Shack?

And is there anything I should know before I go and try to disconnect the EGRC valve to test it -- like how to get the darn plastic cover that's protecting it off without disconnecting EVERYTHING around it. Or any screws that are adjustment screws that I need to NOT touch?

Thanks!!-Amy :-)

[elwesso]

Amy, i think your getting off focus here a little bit... Lets assume that the fuel pump is fine (all can be checked by a simple fuel pressure test).....

I think you need to do DIANGOSTIC PROCEDURE #1 in the EF/EC section of the FSM!!!!!

Here is a picture of the MAF and Main power diagram side by side so we can compare.

[elwesso]

I want to focus here on the pins that are shared between the main power and MAF..

The MAF uses pins:

109*- not sure, probably a relay ground to the ECU.16*- ECCS RELAY (self shut off)26- MAF ground27- MAF signal 49*- Power supply59*- Power supply

* denotes being a shared wire with the main power......

The only thing I could see that you screwed up is you send the 12V base voltage to the ECU... It expects like 4 volts max..

I just dont see how IF you fried the ECU that it keeps clicking on and off like that, my gut feeling is that it would stay off all the time, but its possible that a new ECU may do the trick...

[Amybirds]

Sorry-- I think the heat wave is frying my brain...

I think I see where you're going now.

I'll do Diagnostic Procedure 1 and see what that turns up.

Thanks for your patience!!

[Amybirds]

Update: Just completed most of Diagnostic Procedure 1: We have harness continuity between ECM & ignition coil relay and we have the proper voltage from terminal 45.

In the process, we discovered that the relay that we thought was the ECCS relay was actually the ignition coil relay (thanks to the wiring diagrams). Both relays are clicking when the key is turned to "on", but the ignition coil relay is clicking "louder" than the ECCS relay (even when we switch the relays out between them). Tomorrow after work I'll do the "Check Ground Circuit" but I have a (probably) dumb question: It says to disconnect the harness connector and check harness continuity between ECM terminals and engine ground. So I'm supposed to put one probe on the engine ground screw nearby and one on the various terminals on the harness, right? Or does it go on the actual terminal on the ECU. (ie: do they mean to check the ECM pin terminals or the ECM connector terminals? All it says is the "ECM terminals")

[elwesso]

OK, i had to go back into the service manual to see what you did.. Good job so far!!!!

Anyway, it appears we're nearing the end of this tunnel and we have to find something else to jump aboard... I doubt the grounds are bad, unless something has come detached the grounds dont seem to randomly go bad on the Qs.. Still its a simple enough test to perform just to make sure we dont overlook something.. Definitely go thru with the test!

At any rate, to answer your question, you are supposed to check between the pins on the ECM CONNECTOR TERMINALS. You disconnect the ECM harness, and put the probe on the front side (the part that goes into the ECU) of the connector... The thing here is they dont want to to short out wires when your testing grounds for continuity, so they have you disconnect the harness so you dont screw up the ECU!

Anyway, i just thought of something else..... There are other fuses that have the ECU in its circuit.. probably 2 or 3 other ones.... if memory serves theres 2 in the engine room and one inside the car... Theres a big 30a fuse and a 10a,and then another small one in the car (10a i think). I dont really think thats what the cause of this is, but check them.. CHECK THE FUSES FOR CONTINUITY BEFORE CONTINUING (sometimes they look good but are not)... Also, has your ENGINE CONT fuse blown again?

[Amybirds]

On my way to work but wanted to quickly reply.We haven't blown the ENGINE CONT fuse again. We'll try the grounds and the fuses for continuity tonight after work and see if that leads us anywhere. Post more tonight...

[Amybirds]

Finally had time to work on this tonight...I checked every fuse for continuity and they're all good. I completed all of the Diagnostic Procedure 1 and it was all good.

I did not check the ECCS relay like it recommended, but we have a new relay in there now and it didn't change anything. (If I need to check the relay or all the relays, can you explain how to do this?) ---

I next went to the MASS AIR FLOW SENSOR trouble diagnosis (since that's the part we were messing with in the first place) and found something interesting.

I checked the power supply: The FSM says between A on the MAF harness and ground should be battery voltage but was only .15.

I checked the ground circuit and it has continuity.

I checked the input signal circuit: the FSM says there should be continuity between C on the MAF harness and ECM terminal 27, but there is none.

Now here's what I don't understand: looking at the wiring diagram, I see that the white wire comes out of terminal 27 and goes into A, so there should be continuity between 27 & A. But I don't see any way for there to be continuity between 27 & C (which the FSM says it should have).

In addition, I see a path from C to the battery so it would make sense to me for C to have the battery voltage. But how would the white wire in A get battery voltage (which the FSM also tells me it should have) if all it's connected to is a wiring harness that I've been instructed to disconnect from the ECU before testing.

Am I misreading the wiring diagram and/or the FSM instructions?

Because my MAF terminal A has continuity with 27 and my MAF terminal C has battery voltage, but not visa versa...

[elwesso]

I thought maybe the orientation of the conncetor was bad so i went and checked it on my car, and i have battery volts on pin A to ground.....

As you pull the MAF connector off the MAF, it reads ABC left to right, with the 2 indicator prongs on the bottom, just saying that to clarify the obvious...

I see your concern, by the wiring diagram i dont see how you can have continuity between 27 and C.

I would check for continuity between 27 and A, and 26 and B, i think the FSM may be wrong, because i dont see how its possible like you said.....

maybe later today I do the diagnostic procedures to verify.