Electrical gremlin, I'm stumped.
Thread Starter
Joined: Jul 2002
Posts: 5,093
Likes: 160
From: Defuniak Springs, FL
Electrical gremlin, I'm stumped.
Series 5 here.
Whenever I tap the brakes (to the point that the lights come on) the voltages drops a full 1.0v's. From a good 13.8-9 down to 12.5 or so. Occasionally it will also happen when going over some bumps.
It's really bothering me since I can watch my injector duty cycle drop a few percentage points and my A/F numbers go lean in the split second that it takes to happen. The electical system immediately recovers back to 13.8v within maybe 5/10ths of a second.
A second issue that accompanies this problem is that when I try to start the car sometimes it takes me running the key back and forth a few times to get it to kick the starter over. I can hear it trying to activate the starter solenoid (a very faint clicking noise) and I see the voltage drop like somethings trying to happen (12v down to 10v) whenever I try to start it but usually on the third turn of the key it kicks over immediately and starts the car. I've already gone back under the car and verified the power harness connections are all tight at the alternator, starter and ground at the bell housing. Battery terminal connections are also tight. I think that parts of the power harness are showing it's age with some corrosion.
I know I'm putting a great deal of load on my 90amp alternator (E-Fan, and a full stereo system) but it never did this before. I'm thinking it's one of two things. There is a short in the rear body harness that handles the brake lights, or the power harness that runs to the battery, starter, and alternator. Maybe the alternator is on it's way out? And the starter is too?
Anyone run into this problem before?
Whenever I tap the brakes (to the point that the lights come on) the voltages drops a full 1.0v's. From a good 13.8-9 down to 12.5 or so. Occasionally it will also happen when going over some bumps.
It's really bothering me since I can watch my injector duty cycle drop a few percentage points and my A/F numbers go lean in the split second that it takes to happen. The electical system immediately recovers back to 13.8v within maybe 5/10ths of a second.
A second issue that accompanies this problem is that when I try to start the car sometimes it takes me running the key back and forth a few times to get it to kick the starter over. I can hear it trying to activate the starter solenoid (a very faint clicking noise) and I see the voltage drop like somethings trying to happen (12v down to 10v) whenever I try to start it but usually on the third turn of the key it kicks over immediately and starts the car. I've already gone back under the car and verified the power harness connections are all tight at the alternator, starter and ground at the bell housing. Battery terminal connections are also tight. I think that parts of the power harness are showing it's age with some corrosion.
I know I'm putting a great deal of load on my 90amp alternator (E-Fan, and a full stereo system) but it never did this before. I'm thinking it's one of two things. There is a short in the rear body harness that handles the brake lights, or the power harness that runs to the battery, starter, and alternator. Maybe the alternator is on it's way out? And the starter is too?
Anyone run into this problem before?
Originally Posted by f1blueRx7
Series 5 here.
A second issue that accompanies this problem is that when I try to start the car sometimes it takes me running the key back and forth a few times to get it to kick the starter over. I can hear it trying to activate the starter solenoid (a very faint clicking noise) and I see the voltage drop like somethings trying to happen (12v down to 10v) whenever I try to start it but usually on the third turn of the key it kicks over immediately and starts the car.
A second issue that accompanies this problem is that when I try to start the car sometimes it takes me running the key back and forth a few times to get it to kick the starter over. I can hear it trying to activate the starter solenoid (a very faint clicking noise) and I see the voltage drop like somethings trying to happen (12v down to 10v) whenever I try to start it but usually on the third turn of the key it kicks over immediately and starts the car.
Thread Starter
Joined: Jul 2002
Posts: 5,093
Likes: 160
From: Defuniak Springs, FL
Originally Posted by Go48
This could be your ignition switch going south or a weak battery. Speaking from personal experience, ignition switches do wear out and fail.
I would guess a bad connection at the battery terminal. Although when I had that problem when I went to start it all the power went away instead of the gauge just dropping down a few volts. You can always check it with a DMM.
Thread Starter
Joined: Jul 2002
Posts: 5,093
Likes: 160
From: Defuniak Springs, FL
So heres what I'm going to do for now:
1.Take alternator to shop and have it bench tested.
2.Have automotive electrical shop re-loom a new power harness.
3.???
4.Profit.
1.Take alternator to shop and have it bench tested.
2.Have automotive electrical shop re-loom a new power harness.
3.???
4.Profit.
Thread Starter
Joined: Jul 2002
Posts: 5,093
Likes: 160
From: Defuniak Springs, FL
Anyone having this problem and finding this in their search... My problem was a bad battery harness. Specifcally the alternator side wiring had eaten itself inside and it would read 14.1 v at the alternator post, but 12.8 on the battery itself with the car idling.
The solution is to replace the battery harness, however as a more temporary solution until I can find a suitable replacement is to run a 4 gauge wire from the positive battery post to the alternator directly.
The solution is to replace the battery harness, however as a more temporary solution until I can find a suitable replacement is to run a 4 gauge wire from the positive battery post to the alternator directly.
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