[flash]

the durametric does work with a mac, but you have to boot in windows to use it



i have never done diagnostics with the durametric with the engine running. it has always been with it off, but just the key on. i have done logging with it running though.

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[jfrahm]

It's not guesswork if you use a procedure to test and verify. Something fundmental is clearly not right and it could be that you have not found it due to a wrong assumption, or a test you have not yet performed.



You say your DME relay is bad, how do you know? Are you sure that your jumper is correct and installed correctly?



Is there power to pin 30 at the DME relay socket?



What about pin 86?



I suggest checking for power at pin 7 on the DME connector also with the key on.



I'd really like to see the DME boot up. I wonder if your ignition switch might be bad?

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[Cloud9...68]

Joel,



To answer your questions:



I'm assuming my DME relay(s) are bad because with either of them in place, the fuel pump doesn't turn on when I turn the key to the start position. When I jumper terminal 87 (which I realize is for the DME), 87b, and 30, the fuel pump turns on immediately. I assume the ingition switch is good because I can crank the engine. I have not, however, checked for power at the DME relay terminals. I'll also check for power at pin 7 on the DME tonight when I get home (and I'll have to look up what that pin does...)



Thanks for your inputs - they're much appreciated.

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[Cloud9...68]

[quote name='jfrahm' timestamp='1357938851' post='137316']

It's not guesswork if you use a procedure to test and verify. Something fundmental is clearly not right and it could be that you have not found it due to a wrong assumption, or a test you have not yet performed.



You say your DME relay is bad, how do you know? Are you sure that your jumper is correct and installed correctly?



Is there power to pin 30 at the DME relay socket?



What about pin 86?



I suggest checking for power at pin 7 on the DME connector also with the key on.



I'd really like to see the DME boot up. I wonder if your ignition switch might be bad?

[/quote]

Joel,



OK, here's what I found relative to the DME relay and its socket terminals:



- When I run through the tests of the DME relay described in Clark's garage, it passes them all. So my belief that my DME relays are bad appears to be incorrect



- There is +12V at both pin 30 and 86 at the DME relay sockets



- With the key ion the start position, there is +12V between pins 85 and 86 (suggesting the DME relay should be able to allow power to go to the DME)



- However, there is 0V between pins 85b and 87 with the key in the start position. This appears to explain why I don't hear the fuel pump when I have the DME relay in place, and I turn the key to the start position (the fuel pump does, however, turn on when I place a jumper between pins 87b and 30)



- There is 0V at pin 7 of the DME connector with the key on. Why did you suggest checking this particular pin? According to the manual, it goes to the mass air sensor.



So, I appear to have multiple problems:



1. The fuel pump doesn't turn on when I move the key to the start position, apparently because I don't have +12V at the DME relay socket pin that's needed to energize the coils in the relay to close the switch to activate the fuel pump's circuit.



2. I'm not getting any spark at the spark plugs



3. The CEL doesn't blink when I attempt to perform the blink test



It sure would be nice if I could find something these problems have in common. Tomorrow I'll check to see if I'm getting a signal from the speed/reference sensor (or is it sender?).

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[flash]

this really sounds like a basic "non-supply" issue



when you checked the DME fuse, did you check the circuit for voltage post fuse, or did you just pull the fuse and look at it?



are you sure the ignition switch is going to the "start" position? have you checked voltage at that pin?



have you checked all of your multi-pin connectors? those things are horrible, and fail a surprising amount.

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[Cloud9...68]

Flash,



As far as the supply side, I'm getting +12V into the DME, as measured between pins 18 and 24 on the DME connector when the key is in the start position. So, I'm getting power into the DME. But I'm interpreting the fact that the blink test isn't working as an indication that nothing is coming out of the DME. So, I did only check the DME fuse, and not the voltage post fuse, but the fact that I am seeing 12V going into the DME connector tells me that things are OK post fuse.



As far as the ignition switch, that's a good question. I'm turning it all the way clockwise to the last position before it engages the stater solenoid (and cranks the engine), so I'm pretty sure I'm moving it to the right position to do the blink test. The CEL light does come on, it just doesn't start blinking when I push the throttle to the floor. Is there anything other than a dead DME that you can think of that could cause the CEL light to not blink? It did work before I took the car apart. However, it is suspicious that I'm not seeing voltage across DME relay terminals 85b and 87 in the fuse box (these are the terminals that send current across the coil in the relay that energizes the switch for the fuel pump), which explains why the fuel pump doesn't turn on when I turn the key to the start position, even though I've now confirmed that the DME relay itself is actually healthy. I am, as stated in post 44, getting 12V across DME relay terminals 85 and 86, which send current across the coil that energizes the switch for the DME, which makes sense, since I'm getting 12V going into the DME itself. But I did have to tap into the ignition switch's wiring to activate my new headlights, so maybe I messed something up in the process of doing that.



I haven't checked all my multi-pin connectors, although I inspected them pretty carefully when I re-connected them, and sprayed them all with electrical contact spray, so I'm reasonably confident I don't have any corrosion issues at the contacts. Do you think a problem with one of these connectors could explain why I'm not getting any spark?



To me, the bottom line is that I took a lot of stuff apart on this car, and I did "interact" with its electrical system a fair bit, in the form or removing several items (the sunroof motor and its electronics, the cruise control unit, the air bag control unit, and the windshield washer reservoir), and I installed a new set of headlights, which required me to tap into the electrical system, so I'm going to have to retrace my steps to try to identify where current that's supposed to be flowing, isn't, while I'm waiting for the spare DME to arrive. On my way to break out the wiring diagrams...

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[flash]

everything you are doing so far assumes that only one source goes to the DME. i wouldn't make that assumption. check everything. the fuses have little tap points on them. check post fuse on anything that goes through the DME (alarm, cluster, central locking, yada yada)

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[Cloud9...68]

Yes, the little I've done so far has only confirmed that the main power supply source to the DME is active. My plan for the weekend to to track down as many of the sources that send signals to the DME as I can, because I'm skeptical that the DME just died while laying around for nearly two years. It's more likely that something I touched that sends a critical signal to the DME is the culprit.



However, I'm not sure I agree that I need to track down every possible source. In other words, while there are 32 test points on the DME connector listed in the manual, only a small handful are listed as possible causes of a no-spark condition, so I will definitely start with those.

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[flash]

i would not assume that the logic in the DME is limited to the things you think are no-spark items. i can tell you for certain that it is pretty complicated. having messed with the chips, i know of a few things that will create a non-start condition. i'm not saying it's your chip, though it could be. i would absolutely try another chip. my point is that the DME reads a lot of things, and makes decisions based on that.



since you didn't change all that much, i would suspect something like a power connection to one of the components the DME checks before allowing you to start the car. i think there is even a stereo wire that connects to the alarm that has to be grounded or something in order for the car to start.

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[John]

Cloud, re. not being able to initiate the blink test ("The CEL light does come on, it just doesn't start blinking when I push the throttle to the floor. Is there anything other than a dead DME that you can think of that could cause the CEL light to not blink? It did work before I took the car apart.")

Maybe a long shot, but if the throttle cable isn't taught, it won't rotate the throttle position sensor far enough to signal the ECU to start the test. Happened to me.

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[flash]

or the TPS is disconnected, or not calibrated properly?

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[Cloud9...68]

I tried my stock chip - no change. I tightened the throttle cable a bit when I re-connected it, as it had a bit more slack than I thought it should, so I'm sure it's tight. I haven't checked the <acronym title='throttle position sensor'>TPS</acronym> lately, but I checked it very thoroughly several years ago when I had a hesitation problem, and it was perfect. I will double-check the connection. Just for grins, I also took a close look at the distributor cap and rotor, and they both look fine, and seem to be installed correctly.



Flash, your comment on the stereo wire is interesting. Other than the lack of spark or fuel (Other than that, Mrs. Lincoln, how was the play...?), most everything else seems to be working - power windows, lights, power mirrors, etc., with the exception of the radio. I disconnected and removed the long-expired Sirius radio, which was tapped into the main radio, and I remember being very apprehensive about the number of wires I had to cut/disconnect to get the Sirius radio out of there, so I wasn't surprised to find the radio doesn't work. But the fact that you think the radio has a connection to the alarm, which can cause a no-start condition, tells me I should prioritize bypassing the alarm as my next step. Thanks.

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[banditsc]

Have you tried plugging back in some the computers you removed, paticularly the air bag computer? It appears to be tied to a number of systems, including the alarm.



I

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[Cloud9...68]

[quote name='banditsc' timestamp='1358036257' post='137358']

Have you tried plugging back in some the computers you removed, paticularly the air bag computer? It appears to be tied to a number of systems, including the alarm.

[/quote]

I sold the air bag control module, so that's a no-go, but I jumpered the connectors for it in the prescribed manner, so I'm assuming that's not my problem, but who knows? And I can't think of any computers I actually removed; just a bunch of connectors to things like the headlight motors, windshield washer pump, cruise control, etc., and I wouldn't think these would prevent the DME form getting the information it needs to send a signal to the ignition system to produce a spark.



As far as bypassing the alarm, I'm striking out. There is a nice write-up on Clark's Garage about how to do that on a 944, but the 968's alarm is completely different, and I haven't found, on this site or on R.L., any instructions on how to do this (although there are plenty of unanswered inquiries as to how to it). Anybody have any idea as to how to bypass a 968's alarm? This would be a major data point in my troubleshooting effort.

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[kwikt]

There is a guy on Pelican 944 forum trying to bypass his alarm on a 944S2. Might check it out.

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[Cloud9...68]

As I think about it, the fact that I'm getting voltage at the 86 socket for the DME relay argues against the alarm being the problem, because this socket energizes the coil in the relay that completes the circuit to send current to the DME. I would think that if the alarm immobilizer were active, it would shut off the flow of electricity to the DME relay. Does this make sense?



I'm back to thinking my problem has something to do with my speed/reference sensor. I'm not picking up any voltage at either of the DME sockets for the speed/reference sensor when I crank the engine, and there isn't a hint of any tach needle bounce. I'm wondering if I either connected the speed/reference sensor incorrectly, or didn't set the gap correctly. This thing is buried way in the back of the engine, though - getting to it sin't going to be a whole lot of fun...

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[MB968]

Cloud, you may already have ruled out the crank position sensor. But, just in case I ran the same kind of check described in my Mazda diagnosics manual on a used 968 crank positon sensor (my 968 engine ran with this used one until I took it off due to a cracked connector). If you check the resistence between the center pin on the sensor (yellow wire on my sensor) and the two outside pins, one should give on the order of 980 ohms (a black wire on my sensor). My Mazda diagnostics manual allows about a range of 10% on the resistence reading (the sesnor is different, so for the Mazda the acceptable range of resistence is 520-580 ohms. If you check resistence to the other outside pin, it should show no continuity (ie extremely high or infinite resistence, no reading). This pin is the sensor ground.



And, I like the idea of connecting LEDs to check the sensor at the ECU, mentioned in another thread of yours. My TecGT has this feature built in, and at a glance lets you know when you crank the engine, that the ECU is getting the signal it needs to start the engine. If you get this working for the DME, you'll have to let us know how it goes. It may be a feature that I'd like to install for later diagnostics.

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[Cloud9...68]

MB,



Actually, there aren't a whole lot of things I've completely ruled out yet, and the crank position sensor isn't something that I had even considered, so thanks for the suggestion. However, I have to admit, despite having completely disassembled and re-assembled my engine, I don't know what it is. Could you tell me where it's located, and maybe post a picture of yours? Or is it what I've been referring to as the speed/reference sensor, which is located on the bell housing?



And yes, if I end up using the LED method (something I ran across on the general 924/944/968 forum on R.L.), I'll definitely post on how it went. Thanks.

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[MB968]

Cloud, I am talking about what you call the speed/ref sensor, the one I posted a pic of a day or so ago. I'm using the generic name for the sensor. The DME uses it to know the position of the crank every 6 degrees (from the 60 -2 tooth wheel) mounted on the flywheel. From the amount of time between the pulses the DME calculates the engine speed/rpm and the rate of change in rpm (the derivative of the rpm). It uses this info for various decisions it mades about running the engine. Because of the 60 -2 tooth wheel, the 968 DME can make adjustments every 6 degrees of engine rotation. My '94 Mazda from the factory only had a 6 tooth wheel, so the ECU was only updated every 60 degrees which was typical of engine control during the 90's. When I installed the TecGT, I had to install a 60 -2 tooth wheel. With it the ECU, or our DME can make adjustments 60 times per rev of the engine allowing for much better control and safety (ie, fuel, ignition, knock control, etc.)



One other sensor that might play in the DME decision making is the cam position sensor. On the 968 this is the hall sensor that is in back of the cam pulley that the timing belt is on. On my Mazda, if this sensor isn't working the engine will still start in a "limp" mode. I don't know if this sensor has to be working for our DME to start the engine. I thought I remember seeing that the 968 runs in batch fuel injection mode rather than sequential mode. If this is the case the DME probably doesn't need this sensor to have the engine start. But, I am not sure. Hopefully someone else will know and post here.

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[Cloud9...68]

Thanks for the clarification. The fact that I'm not getting a hint of tach needle bounce seems to indicate some sort of issue with the speed/reference sensor (can someone explain the connection between the tach needle and the speed/reference sensor?), so my project for tomorrow is to remove this sensor and set its gap to 0.8 mm. It's avery tight fit back there - sure was nice with the engine out of the car! Then I'll check its operation using the diode method, although I don't know how to determine which direction the diode needs to be connected between pins 48 and 49 on the DME connector. Hopefully once the speed/reference sensor is installed correctly, I'll be able to use a multimeter to determine the relative polarity of the two sockets.



As for the hall sensor, my understanding is that a bad one won't prevent a 968 engine from starting - it'll just run poorly.

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