Pelican Parts Forums - 911SC only starts with alternator disconnected

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anthony

07-02-2015 06:06 AM

I have a Fluke 73III multimeter. A few posts back I posted my results. How will a test light work differently? Are there settings on the Fluke that will simulate a test light?

rick-l

07-02-2015 07:08 AM

Quote:

Originally Posted by anthony (Post 8692987)

I have a Fluke 73III multimeter. A few posts back I posted my results. How will a test light work differently? Are there settings on the Fluke that will simulate a test light?

Because you want to know that the resistance to ground through the alternator with the air plate switch closed is low enough to allow the relay that drives the fuel pump to pull in.

You didn't mention any numbers with the air flow switch test and I think there is supposed to be a ground closure when the plate is active.

With your meter you could go to pin 85 on the relay and see that it goes to ground (near 0 Volts) when you lift the plate.

anthony

07-02-2015 07:20 AM

For the air flow switch test I hooked up a volt meter. It read 12 volts and then when I lifted the plate it fell to zero. Would measuring the resistance with an ohm meter be helpful?

I'm more than happy to run out and buy a test light this morning if it gives me the right info to diagnose the issue.

rick-l

07-02-2015 07:50 AM

If that is the case what is this?

Quote:

Originally Posted by anthony (Post 8692474)

Test #3
Relay installed
key turned to on position
86 --- 12v
87 --- .03v (should be zero)
87a --- 12v
85 --- .14v
30 --- .02v

Should be 12 Volts with the air flow plate at rest.

anthony

07-02-2015 08:05 AM

That is testing with the relay in the socket and the key on. I was just testing from ground with the volt meter and the positive terminal on the relay pulled out of the socket a little bit. (I admit and mentioned that I wasn't sure if I was performing test#3 correctly.)

For the air flow switch test I hooked up a volt meter to the battery (+) and hole 85 of the FP relay socket (no relay installed). It read 12 volts and then when I lifted the plate it fell to zero volts.

I'm more than happy to run out and buy a test light this morning if it gives me the right info to diagnose the issue.

rick-l

07-02-2015 08:49 AM

Quote:

Originally Posted by anthony (Post 8693189)

For the air flow switch test I hooked up a volt meter to the battery (+) and hole 85 of the FP relay socket (no relay installed). It read 12 volts and then when I lifted the plate it fell to zero volts.

Any chance you have some small wire (like 30 ga wire wrap wire) you could wrap around pin 85, plug the relay in and measure the voltage? Plate at rest - 12 Volts, plate active 0 Volts, the relay clicks and the pump runs.

EDIT: and it seems the voltmeter readings should be opposite of what you describe

T77911S

07-02-2015 08:54 AM

Quote:

Originally Posted by anthony (Post 8692987)

I have a Fluke 73III multimeter. A few posts back I posted my results. How will a test light work differently? Are there settings on the Fluke that will simulate a test light?

a test light provides a load for the circuit. a MM does not. where a MM can mislead you is if it reads 12v but there is a bad connection and there is not enough current to operate the load.

the other thing is a TL helps check for power with reference to ground since the clip should be on chasis ground.
if you need to check the ground side of a circuit, clip the TL to 12v.

boyt911sc

07-02-2015 09:22 AM

Three minute job........

Quote:

Originally Posted by anthony (Post 8693109)

Anthony,

This is a good example of a three-minute job that becomes a major work. For the FP relay and socket test, a test light works best because:
a). You want to see power @ 87a, 87, 86, and 30 terminals with the ignition switch at these positions (OFF or ON).
b). Terminal #85 (FP relay socket) is a ground wire. Use the multi-tester @ continuity setting.
c). AFM switch has two terminals. One goes to terminal #85 and the other one goes to terminal D- (alternator). Test continuity using the multi-tester.

Test your FP relay.
Terminals 87a-30 are NC (normally closed).
Terminals 87-30 are NO (normally open).

When you turn the ignition switch @ ON/RUN;
The NC terminals (87a-30) will be energized if terminal #85 is grounded (at the AFM switch) and NO terminals (87-30) will close.

This is another scenario if terminal #85 is not grounded (open). After you turned the ignition switch @ ON position (not start), the NC terminals 87a-30 will remain closed because the coil is not energized due to terminal #85 is not grounded. With the FP relay @ 87a-30, the FP will run.

This is the reason why you pull the AFM switch to make terminal #85 open (no ground). Follow the logic? Any question?

Tony

anthony

07-02-2015 09:37 AM

Ok, picked up a test light. Will run the tests again and report back. Thanks.

rick-l

07-02-2015 10:49 AM

Oooops this is a little more complicated than I thought.

Here is a good write up thanks to Timmy2
http://forums.pelicanparts.com/8139572-post35.html

What does D- on the alternator do. All the diagrams I see it just goes to ground.

anthony

07-02-2015 10:56 AM

Quote:

a). You want to see power @ 87a, 87, 86, and 30 terminals with the ignition switch at these positions (OFF or ON).

BTW, you said something different in DKLever's topic. In his topic you said, 87 no power. Can you clarify?

I also did another check 87 gets power when the key is turned to the STARTING position and power switches off when the key is turned back to the ON/RUN position.

I'm studying the Bentley manual and this seems correct. 87 is supposed to be a yellow wire to 50 on the ignition switch but it is only energized when the key is turned to START. (assuming I'm reading Bentley correctly)

rick-l

07-02-2015 10:58 AM

87 goes to the start position on the ignition switch

EDIT: so it is working correctly as you tested it

anthony

07-02-2015 11:04 AM

I see that on the schematic so it shouldn't have power with the key in the OFF or ON position. I think my 87 is behaving correctly.

anthony

07-02-2015 03:04 PM

I did the rest of the suggested tests.

Quote:

b). Terminal #85 (FP relay socket) is a ground wire. Use the multi-tester @ continuity setting

Yes, continuity from 85 to ground.

Quote:

c). AFM switch has two terminals. One goes to terminal #85 and the other one goes to terminal D- (alternator). Test continuity using the multi-tester.

I pulled the AFM plug and tested one terminal for continuity to ground (YES GOOD) and the other for continuity to 85 (YES GOOD). Both check out.

Quote:

Test your FP relay.
Terminals 87a-30 are NC (normally closed).
Terminals 87-30 are NO (normally open).

Yes, both show the correct close/open as indicated using the ohm meter to test. I also tested all my other relays and they are all the same. Any there any other test to do on the relay?

anthony

07-02-2015 03:18 PM

I've read timmy2's description of the way the circuit works and it acts like the switch in the relay doesn't close back so that 87a-30 powers the fuel pump. I need a hint as to where to look next.

boyt911sc

07-02-2015 03:41 PM

Confusing information.......

[QUOTE=rick-l;8693092]Because you want to know that the resistance to ground through the alternator with the air plate switch closed is low enough to allow the relay that drives the fuel pump to pull in.

You didn't mention any numbers with the air flow switch test and I think there is supposed to be a ground closure when the plate is active.

With your meter you could go to pin 85 on the relay and see that it goes to ground (near 0 Volts) when you lift the plate.[/QUOTE]

Rick,

Are you familiar with CIS air flow meter (AFM) switch? Your post above is very misleading and would not be helpful to the OP. Have you actually done such investigation before or you simply read about it? This is a technical forum and we could agree and disagree about things and still be friends at the end of the day.

Sharing our experiences with others is good and we learned from each others mistakes too. And your information is contrary to the fact about how the switch works.

Tony

anthony

07-02-2015 04:06 PM

Quote:

With your meter you could go to pin 85 on the relay and see that it goes to ground (near 0 Volts) when you lift the plate.

Pin 85 goes from 12.13v to .08v.

Quote:

Because you want to know that the resistance to ground through the alternator with the air plate switch closed is low enough to allow the relay that drives the fuel pump to pull in.

How would it be best to perform this test? Do I pull the alternator and test right from the alternator minus to 85? And by switch closed you mean air plate lifted, correct?

boyt911sc

07-02-2015 04:22 PM

Read and review post #57........

Quote:

Originally Posted by anthony (Post 8693956)

Pin 85 goes from 12.13v to .08v.

How would it be best to perform this test? Do I pull the alternator and test right from the alternator minus to 85? And by switch closed you mean air plate lifted, correct?

Anthony,

There are a few important things you need to know:
a). Is the FP relay good?
b). Is the FP relay socket good?
c). Is the FP electrical circuity good?

Items a & b could be done under under 5 mins. Contact or PM LJ (ossiblue). He has more patient and articulate than me so I refer him. Read my post #57. You are doing fine just need some guidance and direction. Keep us posted.

Tony

anthony

07-02-2015 04:42 PM

Yes, I need some guidance and direction. :-) And I have read #57 and I'm not sure what to do next.

Quote:

a). Is the FP relay good?

I did the tests you described and the relay checks out. I also tried all the black relays I have with no luck.

Quote:

b). Is the FP relay socket good?

Is there some other test I need to do to determine this that I haven't done?

Quote:

c). Is the FP electrical circuity good?

Previously, I checked the fuel pump. It runs from the relay socket if I jumper 87a and 30. If I do that the car runs great!

boyt911sc

07-02-2015 05:57 PM

Clarification........

Quote:

Originally Posted by anthony (Post 8693501)

I ran through the tests again. The thing that jumps out is no power at 87 of the socket (key on or off). To summarize:

key turned to on/run position
86 ...... power
87 ...... no power
87a ..... power
85 ...... no power
30 ....... no power

I get the same result with the relay plugged in (key on/run position)

I also tested 85 again back to the AFM switch. I put the test light on the battery + and at 85. The light glows. (key off, relay out). Lift the plate and the light goes out and breaks the ground.

According to what you said above, I should have power at 87 so I need to trace back from there.

BTW, you said something different in DKLever's topic. In his topic you said, 87 no power. Can you clarify?

I also did another check 87 gets power when the key is turned to the STARTING position and power switches off when the key is turned back to the ON/RUN position.

I'm studying the Bentley manual and this seems correct. 87 is supposed to be a yellow wire to 50 on the ignition switch but it is only energized when the key is turned to START. (assuming I'm reading Bentley correctly)

Anthony,

In reference to DKlever48's post, there was a subsequent post I inadvertently mentioned about power to 87 and nobody noticed it. Then posted to correct the blunder. There should be no power to terminal #87 with the ignition switch @ ON/Run position. Terminal #87 only gets power when you turn the ignition switch to START position.

I went over to review your test results and everything seems right. But I did not find any test in particular about the FP relay itself. Have you tested and confirmed that the FPR's (FP relay) coil is switching from 87a-30 to 87-30 when energized? The relay could be defective or the contact/s at the socket is compromised. Keep us posted.

Tony

rick-l

07-03-2015 10:05 AM

Let me see if I understand how this system works. I think key to understanding this is to realize the run switch in the air flow meter opens when the engine is running (kind of bass ackwards). Also the wires going to the alternator just provide an engine ground.

Turn the key on
1. Power is applied to terminal 86 (and 87a) of the fuel pump relay (definition from DIN Std. 86 -Start of winding) from circuit 15 (DIN Std. -15 Switched + downstream of battery)
2. current flows through the relay coil, through the closed air flow switch and through the alternator (eventually) to chassis ground.
3. There is a momentary voltage spike at the fuel pump till the relay opens through the normally closed contacts of the fuel pump relay.
4. The relay closes and connects the fuel pump to the yellow wire (control) of the starter. (DIN Std. 50-Starter control (direct))
Turn the key to start
1. The yellow wire is energized which turns the starter solenoid on and runs the fuel pump.
2. The engine sucks air and opens the air flow switch
3. The fuel pump relay coil is de-energized and the relay switches the fuel pump directly to circuit 15 through the normally closed contact(with ~ 20 mSec dead time)
The driver realizes the engine has started and releases the key, with no change in fuel pump power state.
(If) The engine stalls the flow switch closes, the relay energizes (backwards part) and switches the fuel pump to the inactive starter control shutting off the fuel pump

mysocal911

07-03-2015 11:43 AM

Quote:

Originally Posted by rick-l (Post 8694846)

Turn the key on
1. Power is applied to terminal 86 (and 87a) of the fuel pump relay (definition from DIN Std. 86 -Start of winding) from circuit 15 (DIN Std. -15 Switched + downstream of battery)
2. current flows through the relay coil, through the closed air flow switch and through the alternator (eventually) to chassis ground.
3. There is a momentary voltage spike at the fuel pump till the relay opens through the normally closed contacts of the fuel pump relay.
4. The relay closes and connects the fuel pump to the yellow wire (control) of the starter. (DIN Std. 50-Starter control (direct))
Turn the key to start
1. The yellow wire is energized which turns the starter solenoid on and runs the fuel pump.
2. The engine sucks air and opens the air flow switch
3. The fuel pump relay coil is de-energized and the relay switches the fuel pump directly to circuit 15 through the normally closed contact(with ~ 20 mSec dead time)
The driver realizes the engine has started and releases the key, with no change in fuel pump power state.
(If) The engine stalls the flow switch opens, the relay energizes (backwards part) and switches the fuel pump to the inactive starter control shutting off the fuel pump

Yes, it's as simple as that!

boyt911sc

07-03-2015 12:00 PM

Everything looks right except for..........

Quote:

Originally Posted by rick-l (Post 8694846)

Turn the key on
1. Power is applied to terminal 86 (and 87a) of the fuel pump relay (definition from DIN Std. 86 -Start of winding) from circuit 15 (DIN Std. -15 Switched + downstream of battery)
2. current flows through the relay coil, through the closed air flow switch and through the alternator (eventually) to chassis ground.
3. There is a momentary voltage spike at the fuel pump till the relay opens through the normally closed contacts of the fuel pump relay.
4. The relay closes and connects the fuel pump to the yellow wire (control) of the starter. (DIN Std. 50-Starter control (direct))
Turn the key to start
1. The yellow wire is energized which turns the starter solenoid on and runs the fuel pump.
2. The engine sucks air and opens the air flow switch
3. The fuel pump relay coil is de-energized and the relay switches the fuel pump directly to circuit 15 through the normally closed contact(with ~ 20 mSec dead time)
The driver realizes the engine has started and releases the key, with no change in fuel pump power state.
(If) The engine stalls the flow switch opens, the relay energizes (backwards part) and switches the fuel pump to the inactive starter control shutting off the fuel pump

Rick,

This is an excellent write except for the flow switch operation. When the engine stalls, the AFS plate drops down and closes the switch, Not open as you have stated. Maybe a typo?

Tony

anthony

07-03-2015 02:47 PM

I think I'm honing in on the issue. I've ran all the tests again and everything checks out.

While running a test on pin 30 of the relay socket with a test lamp and lifting the AFM plate, I noticed that just as I start turning the key (the moment the gauge lights come on), the fuel pump does run. But, it shuts off as I turn the key farther....

The ignition switch!!!

I made a video. At 4 seconds and 11 seconds in, just as I turn the key the fuel pump runs for a brief moment.

https://www.youtube.com/watch?v=0EnVJgug074

This is repeatable.

And I know:

FP is good
FP relay is good
wiring to the FP is good
FP relay socket tests good
ground and wiring to AFM is good
AFM switch is good
everything I've tested checks out

rick-l

07-03-2015 06:52 PM

Have you thought about hooking the test light up to relay pin 30 to monitor what goes on during a start cycle? You could also monitor it at the warm up regulator.

anthony

07-03-2015 06:59 PM

I realize now that the video doesn't show a lot unless you were there. I had the test lamp hooked up the pin 30 and it did confirm that the fuel pump was getting energized for 1/2 a second just as I turned the key. (I should have included the test lamp in the video.)

boyt911sc

07-03-2015 08:47 PM

This was performed as instructed.......

Quote:

Originally Posted by rick-l (Post 8695466)

Have you thought about hooking the test light up to relay pin 30 to monitor what goes on during a start cycle? You could also monitor it at the warm up regulator.

A test light was connected to terminal #30 with the FP relay installed. This was part of a series of tests conducted to determine the intermittent failure of the FP to run. Anthony noticed that by wiggling the ignition switch key between OFF and ON positions he could momentarily make the test light and FP to come on. And he had replicated this several times.

Tony

rick-l

07-03-2015 09:33 PM

Is that normal for a CIS car? That seems like an awful long time for the relay contact to transfer. Long enough to overcome the inductance in the fuel pump motor and get it to spin (to make a noise).

What happens (light indication) when you turn it to start, start the car and release the key?

mytoy

07-04-2015 04:40 AM

I am of the understanding that this is normal.

It's my understanding that when you turn the key to the start position that the fuel pump will be energized for 1 or 2 seconds then be de-energized when the relay switches over to the starter relay circuit.

This was done to prime the system just before start up.

I think that if Rick's point #3 is correct that it confirms this. Also I recall that Tbitz had to modify the megasquirt program to do this same operation when doing the EFI conversion.

I may be totally out to lunch but I thought that Porsche implemented this in their circuit and therefore the one of the reasons for the red relay to allow for this delay in switching.

As I said I may be totally out to lunch on this. If so disregard.

anthony

07-04-2015 09:27 AM

Yes, did that when I replaced the alternator. The car even ran perfectly with no alternator installed. I probably started it 20 times to move it around. After the new alternator was installed the car ran great briefly. Voltage at the battery was good, thus the new alternator was working properly. And then it stopped running again!!! I thought it was related to the alternator so I was led down the wrong path initially.

Tony really helped me step back and test each component step by step. I really appreciate Tony's aid in helping me set up proper tests to check the FP, relay, socket, AFM switch, etc. And now I have this great understanding of the FP, relay and starting circuit.

The car is still not fixed but a new ignition switch has been ordered from Pelican. I heard it's a pain of a job but will be nothing compared to the days and days I've been banging my head against this problem. Hopefully, we'll be up and running next week.

Quote:

What happens (light indication) when you turn it to start, start the car and release the key?

Is that question for me Rick? What has been happening is that the FP runs with the key in the START position but doesn't run in the ON position. The AFM switch works and 87a has power, and the relay bench tested fine. None of the tests pointed definitively to the problem.

mysocal911

07-04-2015 11:16 AM

Quote:

Originally Posted by anthony (Post 8696143)

The car is still not fixed but a new ignition switch has been ordered from Pelican. I heard it's a pain of a job but will be nothing compared to the days and days I've been banging my head against this problem. Hopefully, we'll be up and running next week.

Is that question for me Rick? What has been happening is that the FP runs with the key in the START position but doesn't run in the ON position. The AFM switch works and 87a has power, and the relay bench tested fine. None of the tests pointed definitively to the problem.

You should be able to jumper #30 power to the FP fuse, and the engine should start
and run normally. This will bypass the #15 power provided by the ignition switch if it's
really bad and power the FP relay pins.

Since there's just one #15 contact on the ignition switch, no #15 power will be provided
to any other electrical requirement, e.g. the light/radio, if the switch is bad. So before actually
replacing the ignition switch, you need to use your test-light to check the various powers at
the ignition switch, i.e. X (if it has one), #15 (run), #30 (constant power), #50 (start).

rick-l

07-04-2015 01:03 PM

With the test light on the circuit that connects to the fuel pump, pin 30 of the relay or the warm up regulator, what does the light show when you start the car and it stalls?

Does it flash when you turn the key on, come on with the starter and then stay on or go out when you release the key? It sounds like everything works except power to the fuel pump with the flow switch on (open).

Quote:

Originally Posted by anthony (Post 8692177)

There came my inspiration. I jumpered the fuel pump and then started the car. The car fired up and ran perfectly.

anthony

07-05-2015 06:38 AM

Quote:

Originally Posted by rick-l (Post 8696387)

The test lamp flashes briefly and then goes out at the moment I start turning the key towards ON. (AFM lifted) (it happens at the exact moment the gauge lights go on. The TL should stay on.

rick-l

07-05-2015 06:48 AM

Quote:

Originally Posted by anthony (Post 8696947)

The test lamp flashes briefly and then goes out at the moment I start turning the key towards ON. (AFM lifted) (it happens at the exact moment the gauge lights go on. The TL should stay on.

When you turn the key from lock to on the test light may flash on but that isn't really relevant.

What happens when you turn the key to start and the engine fires and you release the key?

wildthing

07-05-2015 06:57 AM

OT: if you see a post from someone with an almost meaningless name and posts fewer than 10, ignore and do not quote. Those posts have a hidden image linked to some site, most likely to increase their search rank. (More links increase rank.)

BTTT, I see you are in the Bay Area. I am in San Jose. PM me if you need just an extra set of hands, literally. No tech knowledge whatsoever (unless you count computers).

anthony

07-05-2015 08:11 AM

Quote:

Originally Posted by wildthing (Post 8696973)

Thanks for the generous offer. I think I'm very close to fixing it.

I deleted my last responding to that guy. I did notice that image link in the quote. Now the guy is just repeating what I wrote. Hard to believe that this helps someone's business.

mysocal911

07-05-2015 08:34 AM

This problem, like many, has become overly complex. It should have taken 5 minutes at
most to solve and not over 75 posts and more than a week of troubleshooting.

anthony

07-05-2015 01:04 PM

Quote:

Originally Posted by mysocal911 (Post 8697079)

This problem, like many, has become overly complex. It should have taken 5 minutes at
most to solve and not over 75 posts and more than a week of troubleshooting.

Easier said than done, my friend. I had to learn a lot to get where I am with this. Unfortunately, there isn't good troubleshooting guide for each and every one of these components in one place. I looked at the Pelican troubleshooting guide. I've searched the net. People have given instructions in various threads but finding them is like sifting through sand.

mysocal911

07-05-2015 01:44 PM

Quote:

Originally Posted by anthony (Post 8697341)

It appears that you have not fully identified your problem, i.e. bypassed certain power
points and properly tested the ignition switch, but you've ordered a new ignition switch.
Hopefully this will not be a waste of time and money. The "shotgun" approach to parts
replacement does work on occasion, but not always.

anthony

07-05-2015 02:05 PM

I agree and I realize I'm taking a $100 chance on an ignition switch. And, if that isn't the case I've gotten a lot better with the test lamp and multimeter. :-)

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