jimmydanny

Hi!

I am having issues with my ignition, no spark at all. I got 12V in on the B/Y wire into the coil/igniter, I got working plugs and wires.

What I can read from this is: CAS or ECU...

satch

iTrader: (1)

Do you know if the ECU is powered w/key to on? If you measure the Brown/White wire at the TPS or Boost Sensor w/key to on and it has about 5 volts then it is. If it doesn't then make sure the White/Blue wire at the Main Relay has constant voltage.

jimmydanny

Main Relay is located where? I will check it before the drinking starts in 12 hours :P

I unhooked the UIM to check the ECU ground, can I connect the TPS straight, or do I need the UIM tightened? Is the TPS grounded through the UIM would be the right question.

Jim, Norway

satch

iTrader: (1)

Bolted to the driver's side fender and it has two plugs, one has two wires and the other has four. W/key to on the constant voltage on the White/Blue wire is passed on to the B/W wire at the Main Relay's four wire plug. If the main engine ground is connected properly then everything should be good to go. TPS is grounded through the ECU which is grounded via the engine ground.

-RotorDemon-

Try a new leading coil.

jimmydanny

All coils are the same no spark, tested with 2 plugs, 2 plug wires, all coils. Same thing. So if it is the coils, I really got the odds against me!

satch

iTrader: (1)

If the ECU is w/o power the engine won't do much of anything.

jimmydanny

I know, that is why I am testing that later today. Just answering the bloke over here, just forgot to put his name in my post first.

Anyways, if it isnt this, the last thing to check is the CAS, and then the ECU, right? So I know where to look next if the Main relay is doing its job.

jimmydanny

You sorta saved my day. Ign key ON (the buzzer went off for low water, so it was on), 0.94 volts on the TPS brown/white (both, two of them), and the Pressure Sensor/MAP, brown/white.

What does this mean to me? Main relay fried? If so, is this something I can find at my local hardware store, or is this car specific?

satch

iTrader: (1)

It would appear that something is dropping the voltage down from what it should be and disconnecting the plug from the AFM and retesting the voltage on the Brown/White wire w/key to on should be in order. And does the B/W wire in the four wire Main Relay plug have 12 volts w/key to on?

jimmydanny

Wiring diagram that includes the main relay? cant find it :/ If I can find that, I can test the relay straight on the battery.

satch

iTrader: (1)

Testing the relay at the battery is not much help as you know part of the relay works since the B/Y wire at the coils have power w/key to on. What you need to know first off, does the W/L wire have constant power and then w/key to on does the B/W wire have power or not ( and both wires as already stated are in the four wire plug of the relay).

jimmydanny

I will check later tonight or tomorrow, Ill have to see.

Does there exist a proper list of all color codes for wiring diagrams?

B=Black
W=White
Y=Yellow
G=Green
L=Blue
R=Red

Some Light colors, and combinations of two like BY. But this list is very short I guess, would be niceto have them all written down for the future.

jimmydanny

Oh,one more question. Can I temporary replace my main relay with one or two regular SPST or DPST? Or one of the other two of course.

It would make it easier while waiting, people are still in christmas-mode, and I wouldnt get a new (used) relay here until mid-end of next week.

And as far as I know, a relay is a relay, it is a heavy duty remotely controlled switch (switch controlled by a remotely placed switch to use thinner wires and weaker switches), and the regular ones you get at a gas station would in theory be the same as the one in my car?

satch

iTrader: (1)

No one stated that the relay is bad. The B/W wire should have voltage w/key to on in the four wire plug . If it does not then there are two possibilities as either the White/Blue wire is not feeding the relay w/constant voltage or the relay is bad. If the W/L wire is w/o constant voltage then the B/W wire cannot have battery voltage even if the relay were good. This is the third time I have had to say the very same thing. Enough is enough, just check what has been recommended or figure it out yourself.

jimmydanny

I am going from the fact that the relay is broken, because if it is, I will have to get some temporary ones if possible NOW, as the stores close soon.

However, if I don't have power up to the relay, I used 20$ on some relays, poor me. I am just safing out here, as I want my car up and running as fast as possible.

But I will check it as soon as possible. If the B/W doesnt have voltage, either the relay, or the W/L is not working/getting power at all.

I know what you are saying, but I am looking for a (temporary if needed/possible) fix so I can do that tonight, or continue troubleshooting if so.

As you know, forums arent the fastest way of getting answers, so I'd rather be a bit on front with my questions than having to sit around

And, I really do appreciate the help!

satch

iTrader: (1)

If you don't have power to the relay via the W/L wire then that is not a problem w/the relay itself as the W/L wire comes from the Engine fuse box via the EGI fuse. If the W/L wire had voltage and it was not passed on to the B/W wire when the B/Y wire has voltage w/key to on it would be indicative of a bad relay. One minute of time will tell you what's up at the relay.

The relay can be bypassed if needed by jumpering the W/L to B/W and the B/Y to the fourth wire in the four wire plug. Over time this would probably drain the battery so removing the jumpers after using the car or testing it would be a good thing to do.

jimmydanny

I didnt see why I should do it in your order, when testing the W/L was easiest, especially when the relay is inside my house, and the car is not.

I had 7V on the W/L wire, same on the battery, think some light was on through the night. However, that means the relay does get power.

I guess that means the control power (or whatever I can call it) is there, but is the main power to the coils and ECu there? I am not sure, but I tested the B/W wire without the relay present, as I am unsure if that wire is in or out, but I had no power there at all, so I guess that is the main power and it is missing.

As far as I can see on the wiring diagram, the B/W goes through the 80A fuse, ignition switch, 15A fuse, then the relay?

EDIT EDIT EDIT: DIdnt see your last post, sorry. I still tested the mentioned ones. However, there is B/W going in, and B/W going out. Which ones is the proper ones to test?

FAst edit: Except draining the battery, there wont be any damage to anything? Wires or so? Had a friend with an AE86, burnt up from the fuse box. NOT fun, 6 months of rebuilding and refurbishing.

satch

iTrader: (1)

The B/W wire in the four wire plug for the fourth and last time. The stinking relay takes the voltage from the W/L and passes it on to the B/W wire w/the key to on so how could the B/W wire have voltage w/the relay removed? Answer: it cannot.

jimmydanny

Well, there is still two wires not mentioned here, are these not important when jumpering? You got the 4-pin plug, and the smaller 2-pin, I guess these go to the ignition switch, but the wiring diagram does not state what that plug is for. Or it does not mark plugs, only wires.

And no reason to get angry, when Mazda colors two wires with the same color, i have to ask. You said that it was the 4-pin plug ONCE, not four times. So chill out.

As for the 4 pin jumpering, the last one is black/green, just for the record. However, for a more permanent solution, isnt it possible to grab a SPST and use in place of the stock one? Say a 20A made for extra high beams? I cant see the difference, but there is no ampere-marking on the stock relay, so I dont know how much it really can take and does take.

satch

iTrader: (1)

I beg your pardon, but post #4,10,12,15,17 says otherwise so it was actually addressed five different times.

I never mentioned the two wire plug simply because the B/Y had voltage at the coil which means that the two wires in that particular plug must be behaving as they need to. so therefore it's not an issue unless the the voltage on the B/Y wire was sporadic in nature.

And I'm not familiar with which relay other than the stock one would work in its place. Doen't mean at all there isn't one.

Just jumper W/L to B/W (not saying which plug) and see if pin 1B of the ECU has battery voltage or drained battery voltage in your case.

jimmydanny

Satch, btw. The W/L to B/W goes to the ECU power, right? Because the B/Y goes to the coils, which do not have power.

So in theory, I should now have about 5V on the TPS and the MAP, since I have jumpered the relay? In that case, I do not have power on the B/G wire going to the B/Y to the coils. In theory. I havent checked that yet.

But, what if I do have power over both wires, to the ECU and to the coils, where can the problem be? Only place I can see it being is the ECU itself or the CAS?

satch

iTrader: (1)

Read your first post about voltage on the B/Y wire.

And in your first post it states you have an S5 but in your profile it states you have an S4. And the B/G wire feeds the B/Y wire on an S4 and on an S5 it is a White/Red wire.

Pin 3I is the pin to check just in case you car is an S4 and not an S5.

jimmydanny

One problem there. My car is an S4. My engine, however, is an S5. I know they did NOT swap the MAP, it was still a 327 or whatever from an N/A S4.

I do not think they swapped relay and the front harness, only the engine harness and ECU. So the S4 wiring still applies.

Point being, they swapped only the vital parts to get the engine running.

satch

iTrader: (1)

So did the B/Y wire at the coils ever have voltage w/key to on or not? And your ECU and engine sensors are S5 except for the Boost Sensor?