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Jacob's Intermittent No-Start Electrical (Read 893 times)
jacob estes
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Jacob's Intermittent No-Start Electrical
Apr 18th, 2013 at 11:34pm
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I believe I have had several different no-start issues in the couple years I've had this car. I know this hasn't been the only one, but I believe it has been an issue since before I even owned it.

I wanted to go ahead and get this thread started to document what I find and how I fix it.

The issue is a poor connection to the DME relay telling it to open and turn on the fuel pump and DME. I could kill the car by wiggling the relay board or going over a bump.

It runs with the DME Relay jumpered.

I forget if I measured the voltage on pin 86 for the relay which is supposed to be 12v from Ignition Switch. The car is apart now, so it may come to putting some stuff back together to test that.

The biggest obstacle for me right now is that the wire does not go directly from the ignition switch to the DME Relay. So there's a lot of points where it could be bad.

The alarm, which is jumpered, is apparently between the Ignition Switch and DME Relay. I can't find continuity anywhere with a multimeter EXCEPT for between the Alarm 12v Ignition Switch and pin E2.2 on the wire harness under the relay board which connects to the Ground pin on the DME Relay.

The 12v Ignition Switch IN and OUT are jumpered on the alarm plug (because it is bypassed) so it could be connecting either way there.

But, this doesn't get continuity to any actual ground points.

E2.2 does get continuity to actual ground points.

This connection is poor and changes from great to OL depending on how I wiggle the wires. So I believe this is where I need to focus.

I just do not understand it.

Plus, the wires are not the same. So it's not a direct path.
  

1985.5 944 NA
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noahs944
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Re: Jacob's Intermittent No-Start Electrical
Reply #1 - Apr 20th, 2013 at 9:34am
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Jacob, I don't have all the answers. In cases like yours where there are multiple issues the BEST THING TO DO is repair one thing at a time, repair it WELL. Then move on. These intermittant problems can be very frusterating & time consuming, so for the benefit of your mind & the care. Seek & destroy the problems one by one, so you KNOW what you can count on.

If you can wiggle the wire & it more then likely "opens": that's AWESOME bro. The car is telling you how to fix it. A good car! Smiley

<Pick one repair move on>

Based on what you are saying I'd go after the fuse/relay panel first. Or that wire.

Keep in mind some basics:

the following might be of assistance to trouble shoot your fuse/relay panel:

step 1)with a flashlight visually check terminal to connector. verify depth by gently pushing at the connector inside with a paperclip or something, make sure it stays put. If not the terminal might need help staying put.

step 2)drag-test. this is performed when the terminals are staying put in the connectors. proceed with caution! You can do more damage then good if you have a spade (male) connector that is too big. We are checking to see if the fit is snug (like it should be) between the male & female terminals are connected. you need a "drone" male connector. Depending on the size, could you fabricate one out of half a fuse & some pliers (with battery detached)? No slide the male in to the female. should be snug if not, it's been spread & needs repair.

Lastly visually look & wiggly your relay terminals they can fail also.

Best of luck, it seems like you have a good head on your shoulder for this type of work Jacob.
  

non-purist retro-grouch with questionable tastes
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Re: Jacob's Intermittent No-Start Electrical
Reply #2 - Jun 12th, 2013 at 12:33pm
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This is just an update for me collect some resources so I can reference them later, and hopefully someone else will find it useful.

bleu951 on another forum posted this. I still can't find the diagram I was looking for.

Pin 30 4.0 red wire
pin P 1.0 grey wire
pin X 2.5 black/yellow stripe
pin 15 2.5 black wire
pin 50 4.0 red/black stripe
pin R 1.0 red/black stripe

switch positions off, R (accessory), 1 (run), 2 (start)

pin 30 is battery voltage, hot all the time
pin 15 is switched battery voltage, hot only in positions 1 & 2
pin P is hot in positions off and R
pin X is hot in positions R and 1
pin 50 is hot in position 2, starter solenoid
pin R is hot in all positions except off


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1985.5 944 NA
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Re: Jacob's Intermittent No-Start Electrical
Reply #3 - Jun 12th, 2013 at 12:58pm
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On a wire harness Ian sent me, Pin 15 on the Ignition Switch connects to a small 2-row green/black block connector. Pin R does not.

On my car, Pin R has continuity to that connector. Pin 15 does not.

EDIT:

I opened up the Ignition Switch plug on my car and 15 and R were transposed! I switched them back.

Now my question becomes, would this really cause an intermittent cut-off of the DME Relay, especially one responsive to wiggling?


The real bad news is that I am the one that put these wires back incorrectly. I do not remember if when I replaced my ignition switch I put these back together how they looked like they fit originally and then checked online, or checked online and then put them in how I (incorrectly) thought they were supposed to go.

The way this other harness is wired matches what I have found online, and so mine is that way now.


But I can't try starting my car cause I want to do the belts and waterpump!
  

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Re: Jacob's Intermittent No-Start Electrical
Reply #4 - Jun 12th, 2013 at 5:34pm
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Wait back up a moment. You say you wiggle the relay and you can kill the car but if you jumper it, it does not die. Did you replace the relay????

This sounds like a failing relay.
  

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Re: Jacob's Intermittent No-Start Electrical
Reply #5 - Jun 12th, 2013 at 10:45pm
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If at all possible, crank the car first. If you get too much going at one time, you end up getting nothing done. Don't ask me how I know.
  

Jock Ellis: White 1988 944 NA, '73 914 1.7 project, '72 parts car, '68 912 engine (basket case); Gone but not forgotten: '68 912, '72 914-6, '73 914 1.7, '64 1600 SC Coupe, '60 1600 Super Roadster
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Re: Jacob's Intermittent No-Start Electrical
Reply #6 - Jun 12th, 2013 at 10:46pm
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Not by wiggling the relay itself, but the relay board or wires.

But also I do have two DME relays which test out fine.


There is another issue with the wiring where an "extra" wire has been patched in to get power from another relay for something else. I have no idea what's going on there. So I think this might be related.

I know the previous owners were morons. That is all I know about this car beyond what I've done to it.
  

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Re: Jacob's Intermittent No-Start Electrical
Reply #7 - Jun 12th, 2013 at 10:50pm
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I'm just worried that the belts are overdue and I'm not sure if I want to risk it.

I was told they have been replaced, and I am sure they have, but I am not sure about when. The guy I bought the car from was both a moron and a liar and so I know he did not have the belts done himself, and I am sure the owner prior to him did not as it was only six months registered then.

So I believe it was done as recently as summer 2010 but can't know when.
  

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Re: Jacob's Intermittent No-Start Electrical
Reply #8 - Jun 15th, 2013 at 8:00am
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From what I've read on this forum you can get an idea about the belt's quality by inspecting it. If it looks good throughout its length, it is probably going to last long enough for you to determine whether you have solved your electrical problem. Others may want to weigh in on this subtropical of your repair work, though.
BTW, why did the PO decide to sell after only sixonths?
  

Jock Ellis: White 1988 944 NA, '73 914 1.7 project, '72 parts car, '68 912 engine (basket case); Gone but not forgotten: '68 912, '72 914-6, '73 914 1.7, '64 1600 SC Coupe, '60 1600 Super Roadster
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Re: Jacob's Intermittent No-Start Electrical
Reply #9 - Jun 15th, 2013 at 9:46pm
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If it's generally agreed I can do a look-test at the belts then I'll go with that. I would like to see if the electrical side is sorted out before I start another saga.

I think this could have caused some of my problems since the switched wires both get the same voltage but different gauges and so amperage.


My guess is the PO got a "good deal" on this car, and then found out how bad off it was and had to sell it. He was a student and I think without a job. The owner before that I think might have had better intentions but also sold it.

I had no intentions but to drive it and keep up on it and have ended up with most spaces on the bingo board stamped out.
  

1985.5 944 NA
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