[Cloud9...68]

I only had time to test the <acronym title='throttle position sensor'>TPS</acronym> tonight, and it appears to be working. Testing it the conventional way (stuffing the leads of an analog voltmeter into the connectors for pins 1 and 3 at the <acronym title='throttle position sensor'>TPS</acronym>) gives the typical voltage response as I open the throttle - from about 0.4 to 5V with no abrupt jumps. But when I disconnect the DME's connector, and place the voltmeter leads between sockets 53 (labeled as "Signal from throttle potentiometer" in the manual) and socket 24, which I believe is ground, turn the key to the start position, and press the throttle, I don't get any reading. I also tried it with the voltmeter's ground lead connected to a physical ground on the car, and also no response.



To clarify, I checked the manual, and I remembered wrong - there is no procedure described for reading a signal from the <acronym title='throttle position sensor'>TPS</acronym> at the DME connector - it only describes how to test the <acronym title='throttle position sensor'>TPS</acronym> at the sensor itself. Also, I tried testing the signal at the <acronym title='throttle position sensor'>TPS</acronym> with the DME cable disconnected, and I also got no response. So, I'm not sure if the fact that I don't read any voltage at the DME connector means there's a problem with the signal going from the <acronym title='throttle position sensor'>TPS</acronym> to the DME, or if the DME cable simply needs to be connected to the DME in order to read a signal from the <acronym title='throttle position sensor'>TPS</acronym>. I guess the only sure way would be to figure out which wire goes into socket 53, scrape a bit of insulation off of it, plug in the DME connector, and check for a voltage signal. I'd prefer to avoid potentially destructive tests like this, though, unless there is no alternative.

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[MB968]

Cloud, don't think I followed your comments above. So, I'll just say, it sounds like in your first test the <acronym title='throttle position sensor'>TPS</acronym> is getting power from the DME, and when you get a typical ~0-5v reading as you change throttle position.



If the DME cable is disconnected from the <acronym title='throttle position sensor'>TPS</acronym>, you've probably just taken away the 5v supply from the DME. So, if I understand it correctly, if you have the <acronym title='throttle position sensor'>TPS</acronym> unplugged (no wires to it), you won't see any voltage. To test the <acronym title='throttle position sensor'>TPS</acronym> with no power to it, you need to use the Ohm setting on the meter. And, as you change throttle position, it should change in reverse order to the way the voltage changed. So, higher resistance at closed throttle, and very little resistence at wide open throttle.



Hope this helps.

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[banditsc]

Don't look for power at the <acronym title='throttle position sensor'>TPS</acronym> connector, look for ohms at the DME connector. You should get a different resistance reading as you press the throttle pedal.

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[Cloud9...68]

MB and Banditsc,



I guess I'm displaying my ignorance of how the sensors and DME play together (I'm about two days away from ripping this whole mess out and slapping on a pair of weber carbs - wait, I would never pass emissions with that - another brilliant solution down the drain <img src="/forum/images/smilies/968/wacko.png" class="smilie" alt="" /> ).



But I digress. Yes, what you guys say makes sense - I'll check the resistance at pin 53 of the DME connector (relative to pin 24?) as I dpress the throttle. I suspect it will be OK, and that my <acronym title='throttle position sensor'>TPS</acronym> is fine. This puts me back to re-checking the wiring of the 14-pin connector in the passenger footwell, which I'll hopefully tackle tonight.



I'll also do some more research on whether my removal of the air bag control module could be behind my troubles. Any thoughts as to whether this could cuase the absence of a aignal from the DME to turn on the fuel pump and create a spark? Thanks.

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[flash]

all modern cars with airbags have safety programming to prevent fuel from running after the airbags have been deployed. there may be something in our ECU that similarly prevents things from proceeding if the system looks compromised.

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[Cloud9...68]

[quote name='flash' timestamp='1358865988' post='137794']

all modern cars with airbags have safety programming to prevent fuel from running after the airbags have been deployed. there may be something in our ECU that similarly prevents things from proceeding if the system looks compromised.

[/quote]

Yep - I'm thinking removing my air bag control unit is the cause of my problem (although getting the wiring to the 14-pin connector straightened out was definitely something I needed to do anyway). I reviewed the discussion on R.L. dealing with the disabling of the passenger air bag, and it referred to bypassing a couple of sockets in the connector between the air bag and the harness. I've done this, but my situation is different - I need to find the right sockets to jumper in one of the three connectors that go into the air bag control unit. There has to be a way...

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[banditsc]

I have a intermittently bad air bag computer, your welcome to. It suffers from LABLS (Lazy Air Bag Light Syndrome), my own creation, the light will stay on sometimes for up to 10 minutes and then shut off, it also prevented access to the alarm computer. But the car still ran when it was installed. I can't guarantee the airbag will deploy with the controller, in fact I'd say it wouldn't, so it would be a use at your own risk expecting it not to deploy type part.

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[Cloud9...68]

[quote name='banditsc' timestamp='1358874301' post='137803']

I have a intermittently bad air bag computer, your welcome to. It suffers from LABLS (Lazy Air Bag Light Syndrome), my own creation, the light will stay on sometimes for up to 10 minutes and then shut off, it also prevented access to the alarm computer. But the car still ran when it was installed. I can't guarantee the airbag will deploy with the controller, in fact I'd say it wouldn't, so it would be a use at your own risk expecting it not to deploy type part.

[/quote]

Thanks; I appreciate the offer, and I'll take you up on it if I can't find a way to bypass the connector(s) to trick my car into thinking my air bag control module is still connected. I've removed the passenger side air bag, and plan to do the same with the steering wheel by getting a new, non-airbag wheel (it's going to be primarily a track car, so I'll have a harness, so no air bag needed), so I don't need a functioning air bag control module. I just need some way to make the car think the module is still connected. At least that's my current leading candidate for why DME isn't sending any signals out.

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[tamathumper]

That module might help you figure out if that's even the cause or not...

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[Cloud9...68]

I've spent the last several days chasing down which pins I need to jumper to make the car think my air bag control modul is still connected. The good news is that I'm confident I found the right pins. The bad news is that when I jumper them, there no change in my cars behavior - it's still a lifeless hunk of metal, rubber, plastic, and glass. I'll definitely still install the spare ABCM Banditsc graciously sent me when it arrives, but I'm not very hopeful it will solve my problem.



So, I've gone back through the items on my list outside of the ABCM that I hadn't thoroughly followed through on. First, reading back through this long thread, I found a post from Jeol Frahm stating that with the key in the start position, there should be +12V at pin 7 of the 14-pin connector in the passenger footwell. If there isn't, it means the alarm has shut off power to the DME. So I checked it, and saw +12V. So, I'm striking the alarm as a potential cause of my problem.



Next, I re-checked the wiring of the 14-pin DME connector in the passenger footwell. Starting from scratch, I made a fresh table of the pins on the male and female side, and, using the wiring diagram, wrote the wire color next to each pin designation. Then, I confirmed that the wiring diagram was consistent with Banditsc's pictures (it is). Next, I wrote the numbers of the pins on my connector on a piece of masking tape attached to its sides, so I could know which wire went to which pin without having to take the connector apart. Finally, I checked my wires, and they all matched my table. So, the 14-pin DME connector is no longer a candidate.



Next, I went back to the <acronym title='throttle position sensor'>TPS</acronym>. There are two ways to test it - by peeling back the rubber protective cover, and measuring the voltage between pins 1 and 3 with the key in the start position. I had already done this, and found that it works perfectly - it goes from about 0.4V to 5V. The other way is to disconnect the <acronym title='throttle position sensor'>TPS</acronym> connector, place an ohmeter's leads between pins 1 and 3, and watch the resistance as I depress the throttle. This also worked - the resistance changes steadily. But then I tried what Banditsc suggested a few posts ago - I placed an ohmeter's leads between pin 53 of the disconnected DME connector and ground, and depressed the throttle. This didn't show any change - just showed near-infinite resistance. So I tried connecting between pin 53 and pin 24 (the DME ground, according to the manual), and same result. DId I do this test correctly? If so, is the fact that the resistance didn't change as I pressed the throttle a clue?



So, about the only thing I have left is to try connecting a 3V diode between pins 48 and 49 of the DME connector, cranking the engine, and see if the diode flashes. This is a way to test the performance of the crank position sensor without having to use an oscilloscope (how silly of me not to own one <img src="/forum/images/smilies/968/wacko.png" class="smilie" alt="" /> ). But I think this is probably a waste of time, because a bad or mis-gapped CPS wouldn't explain the fuel pump not turning on, or the non-functioning blink test.



So, what else should I check? Flash mentioned using a Durametric near the beginning of my ordeal. Would this likely work, given that there appears to be no signal coming out of my DME? I'm definitely willing to try it if it might point me on a path toward a solution, as I know someone who doesn't live too far away who has one. Does it plug into the DME connector, or the circular diagnostic port? What might it tell me? Thanks.

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[Cloud9...68]

Oh, one other new piece of information. I just tried cranking it, and while there's still no spark, the tach need now DOES bounce as I'm cranking it- probably as a result of getting the wiring of the 14-pinn connector right. So, this completely rules out the CPS, and means there's no purpose in doing the diode test.

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[flash]

the durametric plugs into the circular port



the more you cross off the list, the more it seems to point to the airbag module

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[Cloud9...68]

[quote name='flash' timestamp='1359072625' post='137939']

the durametric plugs into the circular port



the more you cross off the list, the more it seems to point to the airbag module

[/quote]

Could be, and I have a new one on the way, so I'll know for sure in a few days. But I got a pretty good consensus as to which connectors I need to jumper, but I won't know for sure until I get Banditsc's. My concern is that I'm sure I'm not the first person to ever remove their ABCM, so I'm not very optimistic that this is causing my car to act like a pet rock.



Based on my symptoms, what's your feeling about the Durametric? Does it work if there's nothing coming out of a DME, like my case, or does it only measure the output from the sensors to the DME? Sorry to sound so ignorant, but this is just not something I have any background with.

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[flash]

no worries. i don't know what its protocols are. it's pretty picky. for example, it won't work without a chip installed, even if you have an emulator installed. i've never had this sort of problem to test it.

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[MB968]

Cloud I can't imagine how discouraging this must be for you. If I were you, I'd forget trying to jumper items, etc. I'd concentrate on getting all the parts to put the car back together. I suspect you can get a lot of loaner parts off the forums, as there are a lot of sympathetic owners out there. Once you put everything back in if it doesn't run the fuel pump when you turn on the key, you'll be able to concentrate on what the real issue is. Or if it does work, then you can start taking things off one at a time, doing the jumpers, and insuring it will start with each change. When you remove something and the jumpered fix doesn't work at least you will know what to focus on. When you tore it down, you made so many changes it is hard to know which way to turn. It may just be me, but the process I describe, for me would be a lot less discouraging, as I could at least feel like I was on a sure path.



Good luck

Joe



Posted this on the other forum too.

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[Cloud9...68]

Thanks, Joe. But, it could be worse. I could have bought a bunch of Apple stock when it was well north of $600 a share in breathless anticipation of the release of the iPhone 5 (a "guaranteed blockbuster"), only to see it go into free fall soon afterwards. Wait, so I'm actually awake? This isn't really a bad dream? <img src="/forum/images/smilies/968/ohmy.png" class="smilie" alt="" /> <img src="/forum/images/smilies/968/sad.png" class="smilie" alt="" />

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[MB968]

You're right, considering some of the alternatives its not so bad. Keep looking at it that way. You'll have that race car running soon enough.

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[Cloud9...68]

Maybe my sarcasm was too vague - I'm presently the owner on not only a phantom race car the only Manti Te'o could love, but a boatload of Apple stock that looks like it's on its way to making some might fine wallpaper...



But other than that, things couldn't be better!



But on a serious note, I am trying to keep in perspective that having a silly, impractical car that I'm having difficulty figuring out how to fire up pales almost comically in comparison to the problems millions of people of grappling with.

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[Cloud9...68]

A possible clue (or maybe not...) - a new piece of data, anyway. With the key in the start position, I checked to voltage at the terminals of the coil. To my surprise, I'm seeing +12V at both the (+) and the (-) coil terminals relative to ground. So, if I'm getting voltage to my coil, why aren't I getting spark?



So, I followed the procedure in Clark's Garage for testing the coil:



Ignition Coil Test

1. Disconnect the ignition coil output wire at the distributor cap.

2. Connect a spark plug to the end of the ignition coil output wire which you just disconnected.

3. Connect a ground wire to the threaded portion of the spark plug.

4. Disconnect the ignition coil ground wire from the negative terminal on the coil (Green Wire).

5. Connect one end of a ground wire to the ignition coil negative terminal.

6. Turn the ignition switch to the ON position.

7. Tap the other end of the ignition coil ground wire jumper on an good grounding point (for example the battery negative terminal) and look for sparks at the spark plug that correspond to the frequency of your tapping of the ground wire.

8. If you have a good spark at the spark plug, the ignition coil is good.

9. If you don't get a good spark, check for approximately 12 VDC from the coil positive terminal (black wire) to ground with the ignition switch in the ON position. You should also get approximately 12 VDC from the coil negative terminal (Green wire) to ground



I'm getting a spark, alright, but not at the spark plug - I get a healthy spark between the wire I have connected to the coil's ground terminal, and the ground on the car, when I tap the wire to this ground. So, I measured the resistance between the two coil terminals, and got the prescribed 0.4 ohms or so, and also between the coil output terminal and the coil ground terminal, and got about 6K ohms, which is right in the center of the prescribed range. I called my local Advance Auto, but they say they can't test a coil (at least not reliably).



So, does any of this mean anything? I wish I understood the current pathway in this car. In other words, where is the +12V at the coil coming from? The DME? Or straight from the battery through the ignition switch?

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[Cloud9...68]

OK, a major (if unexplained) breakthrough. I talked to Pete of RS Barn, and he told me that actually, the fuel pump doesn't energize when the key is in the start position. I'd been taking the lack of fuel pump hum, and my non-functional blink test, as indications that my DME isn't sending out a signal. But after talking to Pete, I decided to go back and check just for spark, and sure enough, there's spark! It's fainter than I had expected, especially looking through a dusty windshield, and I didn't even notice it after the first couple of cranks, but sure enough, it's there. Unfortunately, I have no idea what I may have done to fix the spark (getting the wiring to the 14-pin passenger footwell DME connector correct is the most probable thing), or maybe I didn't have the plug well enough grounded in my earlier attempts, so maybe I've had it for awhile (it's been awhile since I've tested for it). But anyway, this is a major step forward.





So, my next question is, when is the fuel pump supposed to turn on? At the DME relay terminals, with the key in the start position, I'm getting +12V at terminal 30 (labeled "battery" in the DME relay's diagram), and +12V at terminal 86 (ignition switch). But I'm getting 0V at terminal 87 (power to DME & injectors) and 87b (power to fuel pump). Is this normal? Would somebody mind checking - it's very simple - you just have to pull your DME relay and stick the leads of a voltmeter into these labeled terminals. Thanks.

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