Pretty much everything I know that relates to wiring comes essentially from reading posts written by HAILERS2 and Icemark, etc. When people asked them something related to an electrical issue, which they excelled at, I would copy the necessary wiring diagram and then reread their responses until I understood what in the rats nest they were talking about. Over time, what they said made more and more sense. And in the whole schematic of things, the wiring for these cars is fairly basic as compared to what goes into today's cars.

Not very likely at all, but make sure the alternator is locked into place for if it loosened up some it sagging could cause the alternator to snap off the rear of the Thermosensor and also possibly cause the fuse to blow in the first place.

You electrical gurus amaze me. It took me 2 days just to sit down, deloom, and label a t2 harness. Probably doesn't help that I can't differentiate between colors too well haha

OK Satch, got the new Thermosensor in and the reading dropped at pin 2I to 6.5 volts. This is still higher than the 2 to 3 volts you said I should see.

Here are all the readings now and they are pretty much the same as before except 2I:

2A = 4.9 v
2I = 6.5 v **

3A = 0 v
3C = 11.5 v
3E = 10.5 v
3G = 0 v

So it seems something else is going on. What do I do now?

Thanks again.

Make sure the plug to the Thermosensor doesn't have one of its wires pulled back within the plug for starters. If this is absolutely not happening then unplug the Thermosensor and remeasure the voltage at pin 2I w/key to on and see if it changes from the current 6.5 volt reading.

Hi Satch, could you clarify this a bit. I'm not quite understanding what you mean by "pulled back within the plug"

Thanks.

There are two wires that feed into the plug. Inside the plug the wires make contact w/the Thermosensor. If the wire(s) are pulled back then it doesn't make proper contact w/the Thermosensor. Try pushing on the wires from the back of the plug when it is disconnected and you'll see if they slide or not inside of the plug.

Wires seem secure in plug however, the situation reverted to the same reading that I had before putting in the new sensor.

w/key on:

Connector unplugged from sensor: 2I = 0 volts.

Connector plugged into sensor: 2I = 10 to 11 volts. **

Satch, it seems like something is shorting in that circuit or I got a bum new sensor. What's the best way to proceed at this point?

There's something very fishy going on here. What you should try to do is removing the wire from the ECU plug which is called depinning. You unplug the plug from the ECU and place a very small tool inside the plug from the front of the plug and make it so the wire pulls out from the back of the plug. After you do this place the ECU plug back into the ECU followed by placing a paper clip into the place where the pin 2I wire was and take a voltage reading from the paper clip w.key to on. It should read no higher than the voltage at pin 2A which is 5 volts.

Another thing you can do is unplug the plug from the ECU housing pin 2I and unplug the plug from the Thermosensor. Then turn the meter to ohms and place one end of the meter on the Thermosensor end of the Green/White wire and the other meter lead to the G/W wire at the ECU plug and take an ohm reading w/no key, again, no key in the ignition. It should be low. You're trying to find out what is causing the very irregular voltage reading.

Another thing to do is w/everything hooked up jiggle the wires that are part of the harness that connects to the Thermosensor w/key to on and see if the voltage at pin 2I changes any. You should probably do this first.

Last thing to do is probably a waste of time but it should only take seconds to do and that is place the red meter lead on the water pump housing by the Thermosensor and the black meter lead on the battery negative post and w/key to on take a voltage reading and it should read very close to zero volts.

It's the Engine harness.

Noticed smoke and sparks at the point where it bends back towards the rear on the drives side. Unwound that region, there is a broken wire and others have burned off insulation. Parts people at local Mazda don't carry that harness anymore so I'll try re-insulating with electrical tape and fixing breaks.

Problem is at that point there isn't much slack in the harness so it's tough to work on. Is there some connector on that side so I can free that end. I can't see all the places it goes on that side.

The two wires for the Thermosensor are part of the Emission harness so not sure if you misidentified the harness you have problems with or what. Also, what is the color of the broken wire and also the other wire colors that have burned off insulation?

It's the harness where those two wires connect to the back of the alternator.

After separating the wires apart, 3 are completely broken and 4 have insulation burned off but not broken. The colors as far as I can tell are:

BROKEN: Green/White, Green, Black/White (thick).

LOST INSULATION: Black/White (thin), Medium Brown (thick), White/Black, White.

On a non turbo (your type I hope) the two wire plug that feeds into the back of the alternator is part of the Emission harness (on a turbo it is the Engine harness).

Now the G/W wire is "probably" the wire for the Thermosensor. Take your meter and set it continuity and place one meter terminal on the G/W wire at pin 2I while it is unplugged at the ECU and the other meter terminal to the G/W wire you found broken and see if it rings out. If it does then you have proof that the wire is for the Thermosensor. Since the wire is broken you will choose one part to place the meter on and see if it rings out. If it doesn't then move the meter terminal to the other side of the broken wire. Stuff one terminal into the back of the unplugged plug at the ECU that has the G/W wire so you can leave it and take the other meter lead to the engine bay to find which is the other end of the G/W wire that runs to the ECU plug.

Yup, the G/W wire shows continuity with pin 2I.

Thanks and will update if still not working after fixing all those wires.

Yes, the ohm meter shows continuity with one side of one of the broken G/W wires.

The problem now is that since I have two broken G/W wires, how do I check which of these two other sides goes to the thermosensor wire I found above?

Thanks.

Do the same thing previously but do the continuity test by placing one meter terminal on the G/W wire at the Thermosensor and then go through the possibilities at the other end and when you find continuity you'll have it properly narrowed down.

What is the path of that G/W wire in the emission harness? I a bit unsure about how it's related to the Thermosensor and the course it takes in this circuit.

The wire basically runs straight from the ECU to the sensor w/o any intermediate connectors. The exact path that it takes to get from one end to the other is beyond me.

It depends on how your reading the voltage on 2I.

IF the connectors are on the ECU and the connector is on the water thermo sensor, then you back probe the green/white wrie (2I) with a paper clip or such backprobing the green/white wire at the ECU's middle plug.

IF the green/white wire is somehow not not connected to the water thermo sensors two wire plug, then you might very well read 11 or so volts at the green white wire when backprobing the ECU's middle plug.

IF the two wire plug at the water thermos sensor has a pushed back pin that would explain things. Push back pin meand the green/white wire terminal in the water thermos sensor is not mating with the contact in the sensor itself. IF you pull that two wire plug off the water themosensor and look in the harness plug, both terminals should be even with each other. IF one is pushed back the that means the green/white wire (or the other wire) is shoved back in the plug where it can't possibly make contact with the terminal in the sensor itself. Usually that meas a gentle tug on the green/white wire will cause it to come out of the plug. Means that sucker isn't locked in the two wire plug.

If the two wire circuit isn't being made...................then the ECU defaults to a temp reading of 178* F and that in turn means during START the amount of fuel delivered by the injecotors won't be enough to fire up the car on a cold day. IF the air temp is in the 80's or 90's the car would start a little easier than a 50*F day.

A quick shot of starter fluid in the air cleaner would prove something if your having start problems. If you know you have spark and spraying starter fluid (only a one second spray into the air filter works, no more seconds) makes the car start up for a moment...........then dies, that means to me the injectors are not getting fuel from the fuel rail (usually, not always is the case).

^Thanks for replying on this foreign board. The original poster found that there were several wires severed within the Emission harness, w/the G/W wire related to the Thermosensor being one of them, so he's in the process of finding and repairing the damage. This all started w/his 40 amp EGI INJ fuse blowing repeatedly.

OK, I fixed what I saw in terms of broken wires and burn insulation.

w/key on 2I (plugged) is about 2.6 V and unplugged is 0 V.

There were some changes but no self-sustained start.

I do not need starter fluid to get ignition. However, it's short lived.
Basically, the engine fires up for a second or two then stops and this repeats as long as I keep turning the starter over. It's like something is shutting the engine off after I get it started.

Other pin readings that I took previously w/key on are the same as before and apparently normal.

2A = 4.9
3A = 0
3C = 11.8
3E = 11.5
3G = 0

Go to the Circuit Opening Relay which is Yellow and Black. It's located under the dash and just to the right of the steering wheel column. It has two rows of wires, five in total. On the bottom row there are two wires. One is solid Black and the other is Brown. Jumper these two wires together. This is the same thing as jumpering the fuel check connector but it is more direct. It is possible that the fuel switch in your AFM is not acting properly. If this were the case the car would start up but die rather quickly. Doing this jumper will test this possibility. The other possibility is a vacuum leak of substantial size.

Hi Satch.

Before I saw this post, I checked one thing I forgot about and that was the B/W and W/B wires to the back of the alternator.

Plugged I'm getting B/W = 11.5, W/B = 1.75
Unplugged I'm getting B/W = 11.5, W/B = 0

Haven't done anything yet on any of this but this is different than before.

I'll do what you suggest next but wanted to check in about this first.

Thanks.

W/key to on do your idiots lights generally light light up as they are supposed to when the plug is connected to the alternator. If they don't then check the 7.5 amp Meter fuse.

Idiot lights work fine.

Jumpered the brown and black wires in that connector by the steering column and it did not change the situation.

If a vacuum leak is next then where to check first and how?

Thanks.

It's rather hard to check for a vacuum leak when the engine is not running for if it did run you would spray some cleaner here some cleaner there and the sound of the engine will tell you if you found something. Since you cannot get the engine running you would need to create a tool used to hold vacumm at the intake duct and check for leaks. They make these components for rather cheap but perhaps there is still something else you can do in the meantime. You might want to look over the AFM and see if the flapper moves open when pressed upon w/o much resistance. If it is stuck rather closed then it could cause the engine to die out. Also, you might want to disconnect the single plug to the AFM and w/the Circuit Opening Relay jumpered try to start the car. You also want to review the important fuses to see if they are still holding up. These would be the Comp fuse, INJ fuse and the Engine fuse.

OK, I checked the flapper and it moves easily.
After that I unplugged a big black electrical connector to the AFM.
Again jumpered the brown and black wires under the dash.

THE CAR STARTED!

It ran with LOTS of smoke coming out of the exhaust for a few minutes.
I decided to turn it off and the try again.

On the second attempt I couldn't even get it to initiate the start, it just turned over.

Maybe, it was by chance that these correlated??

BTW, the second attempt wouldn't even initiate with starter fluid.
Battery is getting low and I'm currently recharging.

Nooooooooooooooooooooooooooooooooooooo!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!

The smoke was from all the excess fuel being burned off. You have to let the smoke clear off first. You should not have turned the engine off after all the trouble it has had trying to start. Now its probably flooded once again. You tried to out think the car and now you pay the reaper. You need to pull the lower plugs (make sure they are not wet) and disconnect the fuel pump, disconnect the White plug to the leading coil, disconnect the two plugs w/six wires to the trailing coil and then turn the engine over when the battery is charged enough so as to blow the excess fuel out of the rotor housings. Then try to start the car once again. And when it starts let it run followed by letting it run...........................

We do learn by our mistakes:nod:

So I basically did everything OK but stopped to soon.

OK, so what about that AFM connector and jumping the brown and black wires under the steering column?

Do that again then let it run out and then connect things up afterward? That's what I did previously when trying to start again.

Satch, thanks for the guidance and patience, it's much appreciated.

You might have some interference from the AFM for this or that reason so you should check some of the pins at the ECU which relates to it. Pin 2E should read 4 volts w/key to on. Pin 2J reads 2 to 3 volts when the air temp is 68 degrees (this reading is less important than the first one).

The jumper at the relay is to take the place of one of the roles of the AFM and it causes fuel to flow w/key to on so you don't really want to leave the key in the on position more than necessary to prevent flooding. You can also look in the FSM in section 4A page 54 for the procedure to test the AFM.

Since your only start occurred w/o the AFM I would try it again to get the car running so it could idle and burn off the excess fuel and in the meantime check the AFM according to spec. The AFM does have a Brown wire as part of the Emission harness and possibly this is one of the wires that was damaged. Could it be playing a role in the whole scheme of things? Can't really tell at this point.

Forgot to ask. When you mentioned disconnecting the fuel pump is that actually at the pump or some circuit that turns it on. I have a cut off switch but you seem not to like using that. In any case how do I do that?

Thanks.

You could do it at the pump or pull the Circuit Opening Relay.

Did everything you suggested to de-flood and the car runs.

In fact it started running with little smoke.

However, as things went on and the car eventually got to running temperatures hotter than normal, the smoke progressively seemed to be getting worse. It even seemed to also be coming up in the engine compartment from behind the fuel injector and not just out the tail pipes. Maybe it drifted from the pipes ... but that would be a second guess.

The car eventually stalled as the idle dropped low enough.

I restarted it two more times, smoke was still present and it stalled when rpm dropped low enough.

After all that I checked readings at pin 2E w/key on, jumper removed, & connector replaced at AFM. 2E reads 4 volts.

However, I decided to take a reading at 2I again and it read 0.6 volts!

Pin 2I, Water Thermosensor, should drop to about .5 volts as the engine finally heats up so that is a proper reading you have. You should test the AFM according to the FSM and if it checks out properly then try to start the car w/it connected up. It was good for you just to get the car started but running the car w/o the AFM causes the car to run fairly rich I think so that would perhaps explain why it eventually bogged down in addition to the fair amount of smoke.

AFM checks with all specs. I've been driving it today without problems ... so far.
Thanks again for all the help Satch, it was much appreciated.

if the 15 amp Engine fuse (interior fuse box) is blown, will that cause the "eng inj" fuse to blow
or am i still looking at a grounding issue with the "Eng Inj" fuse?

If the Engine fuse was blown the EGI INJ fuse would not know it. The INJ fuse powers the coils as well as the injectors. Chances are the Black/Yellow wire is grounding out.

Assuming you have an S4, the INJ fuse has a Black/Green wire coming from it that connects to the Main relay at the 4 wire relay plug. When does the fuse blow? Is it when trying to start the car or just sitting there after you replace the fuse? Since the fuse has a Black/Green wire connected to it you can isolate this section of wiring to see if a resistance test gives you any clues. The wire runs from the fuse to the 4 wire Main Relay plug. Disconnect the plug from the relay and w/the fuse pulled from the engine fuse box take a resistance reading on this wire and see if it is abnormally high. If it tests out normal then the problem is likely after the relay but before either the coils or injectors. If the 15 amp Engine fuse was pulled and the INJ fuse continued to blow then the problem is occuring at a point before the Main Relay.

Thanks satch, yeah S4

it had been blowing as soon as i turned it on reds
i disconnected the relay, it didnt blow this time
definitely after the relay somewhere.. its doing my head in

You can bypass the relay by jumpering the Black/Green wire to the Black/Yellow wire and see if that causes the fuse to blow or not. You could also jumper the White/Blue wire to Black/White and attempt to start the car if the fuse does not blow when the respective wires are jumpered. If the car is able to start and run w/o the fuse blowing then there is a problem w/the relay. Jumpering these wires could drain the battery when the car is not in use so this is just a temporary jumpering to help diagnose things. If the fuse blows when jumpered then the wires running to the coils and injectors would be suspect. Doing a resistance test on these wires would indicate where the short is. Also, the injector wires run to one of the large Orange connectors near the ECU before being routed to the injectors. If you believe it is the injector wiring causing the short then you can disconnect the necessary plug and narrow down the short as being before or after the Orange connector.

what readings should i get when i do the resistance test on the injectors and coils?
also i should have mentioned i am running individual coil packs
and a microtech lt10.
I think the big orange wire might be a different colour..?