No start
04-14-2010, 02:36 PM
#16
Rennlist Member
Cam covers removed, too? Any powder coating?
Wondering where you might have a faulty ground.
Lots of wire tracing to perform, and lots of good guidance here via search.
Can be a dozen different things, though. You will need diagrams and a digitial voltmeter.
Best way is methodical. There are some troubleshooting guides in technical publications.
Alternatively, search out any of three dozen no start threads and just follow the advice streams.
Wondering where you might have a faulty ground.
Lots of wire tracing to perform, and lots of good guidance here via search.
Can be a dozen different things, though. You will need diagrams and a digitial voltmeter.
Best way is methodical. There are some troubleshooting guides in technical publications.
Alternatively, search out any of three dozen no start threads and just follow the advice streams.
Last edited by Landseer; 04-14-2010 at 02:53 PM.
04-14-2010, 02:47 PM
#17
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Doug,
The reason for systematic troubleshooting is that it tells you what is wrong quickly and efficiently.
Did you check for power from Q13 to ground? Did you have power there? The answer will instantly split the possibilities in half. It sounds as if you are still blindly poking around...
The reason for systematic troubleshooting is that it tells you what is wrong quickly and efficiently.
Did you check for power from Q13 to ground? Did you have power there? The answer will instantly split the possibilities in half. It sounds as if you are still blindly poking around...
04-14-2010, 03:40 PM
#18
Rennlist Member
Thread Starter
Wally, Sorry.....I did not have power at Q13 .I did have power at the A connection. I also checked power at the starter and got 12+ v there. Also gets power to the jumper in the engine bay. Thanks, Doug.
04-14-2010, 06:37 PM
#19
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OK, some clarification is needed...
If there is no voltage at Q13, there can't be voltage on the yellow wire at the starter.
Where did you have voltage at the starter? The large cable is hooked straight to the battery, so it should always have voltage. The small yellow wire triggers the starter solenoid, and it is the one that is energized when you turn the key to start.
If you have voltage at A23 when you turn the key, but not at Q13, then the most likely causes for the problem include:
- Faulty start relay. Swap Relay XIV (the start relay) with Relay XII (the horn relay). Try the horns - if they work, but the starter still is non responsive, the relay should be OK.
- Bad connection in the front corner of the spare tire well. The neutral start switch circuit goes thru this connector. Separate it and clean both sides carefully.
- Neutral Safety Start Switch faulty or maladjusted. Hold the ignition switch firmly in the start position and slowly move the gearshift lever thru its full range of motion. If the starter responds at all during the movement, the switch might be loose or maladjusted.
Check all of these, and report - in detail - what you find.
If there is no voltage at Q13, there can't be voltage on the yellow wire at the starter.
Where did you have voltage at the starter? The large cable is hooked straight to the battery, so it should always have voltage. The small yellow wire triggers the starter solenoid, and it is the one that is energized when you turn the key to start.
If you have voltage at A23 when you turn the key, but not at Q13, then the most likely causes for the problem include:
- Faulty start relay. Swap Relay XIV (the start relay) with Relay XII (the horn relay). Try the horns - if they work, but the starter still is non responsive, the relay should be OK.
- Bad connection in the front corner of the spare tire well. The neutral start switch circuit goes thru this connector. Separate it and clean both sides carefully.
- Neutral Safety Start Switch faulty or maladjusted. Hold the ignition switch firmly in the start position and slowly move the gearshift lever thru its full range of motion. If the starter responds at all during the movement, the switch might be loose or maladjusted.
Check all of these, and report - in detail - what you find.
04-14-2010, 08:36 PM
#20
Rennlist Member
Thread Starter
Wally, I tested the starter at the starter by touching pos. meter lead to the two large wires and neg. lead to the small wire at the bottom of the solenoid.I might add it looks like there is two places to bolt a small wire to . Mine uses the lower one. I didn't see a yellow wire at the starter. Next ,I swapped the relay seems ok. Next , I cleaned up the ground in the wheel well. Finally I turned key and shifted several times .... nothing. Also re-tested Q13 ( the large yellow wire) Still no juice.
04-14-2010, 09:51 PM
#21
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The standard test for voltage on an automobile is from the connection being tested to a chassis/body/engine ground - that is, to bare metal on the chassis, body or engine. This is the test that you must do on A23, Q13, and all other tests for voltage.
The large cable is hooked directly to the battery, and should always have battery voltage.
The small wire (which should be yellow, but may look brown) comes from Q13 thru the 14-terminal connector on the right fender panel. When voltage is applied to this wire, it operates the large starter solenoid (electrically operated switch and gear operation), which electrically/magnetically slams a metal slug to the other end of the solenoid barrel, closing a heavy-duty switch that connects the starter windings and armature to the battery, and also slides the starter gear into mesh with the ring gear on the flex plate. This spins the engine for starting.
You almost certainly have no power on the small yellow wire. You would check that by having the red wire of a voltmeter on the small connection that has the yellow wire attached, the black wire on bare metal on the engine or chassis, and the ignition switch in the start position.
You said that the relay "seems OK". Did you swap the horn relay and the start relay? Did the horn work using the old start relay?
You were not supposed to clean a "ground in the wheel well". You were supposed to clean a multi-terminal connector located in the forward corner of the spare tire well. Both connections to the neutral start switch go thru that connector, and it is a common cause of your problem.
The large cable is hooked directly to the battery, and should always have battery voltage.
The small wire (which should be yellow, but may look brown) comes from Q13 thru the 14-terminal connector on the right fender panel. When voltage is applied to this wire, it operates the large starter solenoid (electrically operated switch and gear operation), which electrically/magnetically slams a metal slug to the other end of the solenoid barrel, closing a heavy-duty switch that connects the starter windings and armature to the battery, and also slides the starter gear into mesh with the ring gear on the flex plate. This spins the engine for starting.
You almost certainly have no power on the small yellow wire. You would check that by having the red wire of a voltmeter on the small connection that has the yellow wire attached, the black wire on bare metal on the engine or chassis, and the ignition switch in the start position.
You said that the relay "seems OK". Did you swap the horn relay and the start relay? Did the horn work using the old start relay?
You were not supposed to clean a "ground in the wheel well". You were supposed to clean a multi-terminal connector located in the forward corner of the spare tire well. Both connections to the neutral start switch go thru that connector, and it is a common cause of your problem.
04-14-2010, 10:22 PM
#22
Rennlist Member
Thread Starter
Wally, I meant spare tire well. The horn worked before and after the relay swap...... The yellow wire is brown now. I just checked it as instructed and no power . Thanks Doug.
04-15-2010, 12:35 PM
#23
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Go to the connector in the spare tire well. The wires that we need to check change colors at the connector.
At the connector, find:
- A brown wire that changes to violet on the other side of the connector.
- A brown wire with a yellow stripe that changes to violet with a white stripe on the other side of the connector.
Disconnect the connector. Make a temporary jumper so that you can connect the brown wire to the brown/yellow wire. This will bypass the neutral safety start switch. Try the starter. If it now works, you probably need a new safety start switch, or you may just need to refurbish and adjust the existing switch.
If the starter still does not work, test for continuity from the brown wire to ground. Set the meter for the lowest Ohms scale or for continuity, put one lead on the brown wire, one lead on the bolt for the battery ground strap. If there is no continuity (zero or near zero Ohms resistance), MP (ground connection) VI needs cleaning.
At the connector, find:
- A brown wire that changes to violet on the other side of the connector.
- A brown wire with a yellow stripe that changes to violet with a white stripe on the other side of the connector.
Disconnect the connector. Make a temporary jumper so that you can connect the brown wire to the brown/yellow wire. This will bypass the neutral safety start switch. Try the starter. If it now works, you probably need a new safety start switch, or you may just need to refurbish and adjust the existing switch.
If the starter still does not work, test for continuity from the brown wire to ground. Set the meter for the lowest Ohms scale or for continuity, put one lead on the brown wire, one lead on the bolt for the battery ground strap. If there is no continuity (zero or near zero Ohms resistance), MP (ground connection) VI needs cleaning.
04-15-2010, 07:40 PM
#25
Rennlist Member
Thread Starter
Wally, I sent an e-mail to you just in case you didn't get this note. The jumper worked!!!! What's next? I would feel more at ease with a new safety start switch. Do you sell them? Can I run the car without the switch until I replace It.? Thanks, Doug.
04-15-2010, 07:56 PM
#26
Rennlist Member
Rennlist Site Sponsor
Great news! It is so much easier to do systematic troubleshooting than to try whatever worked for someone else. We need the"Here's what my problem was." posts, but we also need to use some logic combined with the info in the manuals.
What I would do next would be to get under the car and locate the switch. It is a complex switch, driving the shift indicator lights as well as the start switch. If your shift lights work correctly, I would check for broken wires, bad connections, etc. between that connector in the spare well and the switch. You do not want to replace the switch unless you really have to do so...
Yes, we sell the switches - but be certain that you really need one first! The switch is located on the left side of the transmission where the shift cable attaches to the transmission. A/T Interlock Switch '83-'95; P/N 000.545.660.6; $81.33.
Our web site lists every part available from Porsche for your 928, with prices. The more common parts are shown by the year model, the less common parts by P/N.
What I would do next would be to get under the car and locate the switch. It is a complex switch, driving the shift indicator lights as well as the start switch. If your shift lights work correctly, I would check for broken wires, bad connections, etc. between that connector in the spare well and the switch. You do not want to replace the switch unless you really have to do so...
Yes, we sell the switches - but be certain that you really need one first! The switch is located on the left side of the transmission where the shift cable attaches to the transmission. A/T Interlock Switch '83-'95; P/N 000.545.660.6; $81.33.
Our web site lists every part available from Porsche for your 928, with prices. The more common parts are shown by the year model, the less common parts by P/N.
04-15-2010, 09:04 PM
#27
Rennlist Member
Thread Starter
Thanks again Wally. My shifter lights only read reverse ,I think, I'll check on that. I've also got to say Your company treated me extremely well when I ordered some things... very satisfied. I have only had the car a short while and have only driven around the neighborhood Can't wait to get her on the road but I still have some sorting out to do. I'm sure I will be asking for help soon .Thanks Doug.
