2013 gauge wiring question.

herairk · 03-04-2013, 01:19 PM

http://www.wrxforums.com/forums/11-d...ost-gauge.html

I followed this guide to fuse block tapping using same taps.

My problem is my aem boost gauge is sweeping on the on positions but when cranking it sweeps again and sometimes shows incorrect reading. I think im losing power during crank, and throwing off the gauge.

Is there a constant 12v that doesn't lose power while cranking in the fuse block? I really don't want to run a wire straight from battery, or tap the stock wiring anywhere if i don't have to.

Thank in advance.

Edit. I used a multimeter and tried to find a constant but either my meter is broken or there is none. I don't know.

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Cougar4 · 03-04-2013, 04:14 PM

To check your meter out simply use it to test the battery voltage and see if it works ok there. Most likely the meter is okay. Make sure you are set up to read DC volts with it.

Most of the dash fuses have no power on them until the ignition switch is turned ON. There are a few like the door lock fuse that should have constant power since they need to provide power without the ignition being on.

A lot of fused circuits are also tuned off while the key is in the START position while power is provided to the starter. This shouldn't affect the gauges though unless there is a connection problem but it will make them reset. To check the voltage at the fuses place the meter probe in the small slit located on top of the fuse. Also, it would be wise to purchase fuse taps if you wire directly into the fuse positions. By providing power directly to the gauges and not though the ignition switch it may cause a current draw on the battery you don't want to have.

herairk · 03-04-2013, 04:25 PM

Quote:

Originally Posted by Cougar4

To check your meter out simply use it to test the battery voltage and see if it works ok there. Most likely the meter is okay. Make sure you are set up to read DC volts with it.

Most of the dash fuses have no power on them until the ignition switch is turned ON. There are a few like the door lock fuse that should have constant power since they need to provide power without the ignition being on.

A lot of fused circuits are also tuned off while the key is in the START position while power is provided to the starter. This shouldn't affect the gauges though unless there is a connection problem but it will make them reset. To check the voltage at the fuses place the meter probe in the small slit located on top of the fuse. Also, it would be wise to purchase fuse taps if you wire directly into the fuse positions. By providing power directly to the gauges and not though the ignition switch it may cause a current draw on the battery you don't want to have.

Thanks fo the response. Yes i checked the meter it was reading fine just straight to the battery. I also did use the fuse taps. I also did use the door lock fuse space for the constant 12v, but i think the door lock fuse cuts power during cranking, causing the aem gauge to reset(sweep) again. It does it every other start. Im running through the wiring again. I placed the tester on the door lock fuse and cranked but my meter didn't show any cutoff during cranking( again my meter is old so it cold be that).

Cougar4 · 03-04-2013, 07:53 PM

Just because the meter is old it doesn't mean you can't trust it. Get a test light probe to do the testing if you don't believe your meter display. I assume you have an analog meter scale here.

I would guess the door lock fuse power doesn't get cutoff with the ignition switch in the START position.

dirrtydetroit · 03-04-2013, 07:57 PM

Here's one to think on, what about the ECM fuse? Shouldn't that have power with ACC and START?

herairk · 03-04-2013, 09:00 PM

Quote:

Originally Posted by dirrtydetroit

Here's one to think on, what about the ECM fuse? Shouldn't that have power with ACC and START?

My guess is yes it should maintain power, im not home ill try when i get home.

Here a little funny thing i noticed. When i start the car with the door open(not latched), I don't get the problem as when i start the car with the door closed. HMMM...I guess the door lock power does not cut(or drop voltage) when you leave the door open while cranking. So for now I guess ill just start the car with my door opened. I just thought it was funny.

herairk · 03-05-2013, 03:08 PM

update tried and tested every fuse in the interior fuse box. every single one cuts out during starting.

If anyone has a aem analog face digital boost gauge on there 08+ please share your wiring and if you have experience the same problem.

Cougar4 · 03-05-2013, 03:25 PM

Quote:

Originally Posted by herairk

Here a little funny thing i noticed. When i start the car with the door open(not latched), I don't get the problem as when i start the car with the door closed.

That statement makes me think there may be a chassis ground problem. Try cleaning the main battery ground wire to the engine and also the battery to chassis ground connection to see if that changes things in the start mode.

Another test you could do to see if there is a grounding issue is place the common meter probe on the negative battery post and then recheck the voltages in the START mode. You may need a jumper wire to do that to extend the length. If some of the fuses now have voltage on them then that proves there is a grounding issue.

herairk · 03-06-2013, 12:34 PM

OK ANOTHER UPDATE. I kept playing with my meter and fuses, and it turns out my constant power 12v that was hooked up to the door lock fuse was good. It was my switched 12v that was cutting in and out causing the gauge to freak. I used the Turn Ignition fuse for the switched 12v and all is good! Just remember before cranking let the the gauge self zero then crank. Dont rush to crank without priming and letting the gauge zero it will not read right.

Cougar4 · 03-06-2013, 01:00 PM

Glad you got it fixed. I guess the interrupted power was causing a problem since it appears that the gauge may be doing a calibration sequence during that time power got interrupted.

herairk · 03-06-2013, 01:28 PM

Quote:

Originally Posted by Cougar4

Glad you got it fixed. I guess the interrupted power was causing a problem since it appears that the gauge may be doing a calibration sequence during that time power got interrupted.

Yes exactly. freakin hell! I was going nuts! haha

salvi · 03-06-2013, 07:25 PM

I'm having the same issue on my aem gauge. If both your constant and switched power is not cutting out, the gauge should work fine even if you don't wait for it to calibrate.

herairk · 03-06-2013, 10:52 PM

Quote:

Originally Posted by salvi

I'm having the same issue on my aem gauge. If both your constant and switched power is not cutting out, the gauge should work fine even if you don't wait for it to calibrate.

But thats how the gauge works. It has to calibrate or zero then when engine is on it starts reading. Mine is working awesome, and reading right where it suppose too.

salvi · 03-07-2013, 01:06 AM

right, but if it loses power again when the car is turned on, the gauge will not finish zeroing correctly.

salvi · 03-17-2013, 05:53 PM

Did more troubleshooting with my volt meter today. I've had the gauge off for a couple of days, but the wiring is still in place. All the wire connections are secured and reading properly.

This is what I've found.

1. Ignition on Acc = Gauge will turn on and calibrate. Reads 12+ volts. Turn the car on from that position and 90% of time it will be fine.

2. Ignition to On= Gauge will turn on and calibrate. Reads 11.7 volts. Turn the car on from that position and 99% of time it will be fine.

3. Crank car from the start= Gauge will turn on and attempt to calibrate, but will stop at 0, the gauge reads inproperly.

So I don't know why the gauge will not calibrate properly if you turn on the car normally.

What I do notice from my voltmeter is that when going from Acc to On the constant power line drops from 12v to about 11.7. When going form the On to cranking, it will drop all the way to 10v, but recover back.

The same thing happens with the Ignition wire, but the drop going from On to cranking is much severe. It will drop all the way to 4 volts.

I wonder if the gauge needs to have a constant flow of power in order for it to calibrate properly and the low voltage during cranking is making it act weird like this. I've had many gauges, including the Autometer ones, and I've never had issues like these before.

Is there any wire on the car that is an Ignition wire but doesn't drop so much current when the car is being cranked over? I'm going to look around all the plugs to see if I can find any.

salvi · 03-17-2013, 06:31 PM

Ok, did some more testing right now.

To verify that the issue is caused by extreme drop in voltage on the ignition wire during direct cranking without waiting for the gauge to calibrate, I connected the ignition wire direct to constant power.

I only connected the wire to constant power right when I went to crank the car over. The issue doesn't occur when connected to constant power and I'm thinking that it's because the constant power source doesn't drop so much in current like the ignition source while cranking.

Another thing I noticed is that the gauge will not calibrate when connected this way when you crank it directly. It will turn on and immediately read vacuum. I wonder if this is the correct operation of the gauge, maybe it only goes through the entire calibration process if you don't turn on the car fully and it's not ready vacuum from the sensor.

I can probably leave the gauge connected this way using a relay that will only give power to the ignition wire when the key is on the Acc power, but will kill that wire when the key is Off. This way you don't have to wait for the gauge to calibrate every time you go to start the car, you can just turn on the car without any worries.

I will setup the gauge like this as a last resort if I don't find a proper ignition wire that doesn't drop so much current while cranking.

Cougar4 · 03-17-2013, 09:01 PM

The battery voltage drops to around 10 volts in the START mode due to the heavy current load of starter motor, that is normal. The 4 volt ignition source isn't what it should be though. It should be close to the battery voltage. There may be some dirty contacts in the ignition switch. You could check the input to the switch and see if that is ok.

You don't want to tie power directly to the gauge as that will cause a drain on the battery. You will need to add a relay to get the power to the gauge.

salvi · 03-17-2013, 11:31 PM

All the Ignition sources drop to 3-4 Volts when the car is cranking over, not one source that I tested doesn't drop. I'm going to connect the gauge to constant power with a relay as stated earlier. It will have constant power, but it will be switched as well.

The Ignition power drops, but comes back to normal after startup and this is what I think the gauge is not liking. I don't know why this gauge is like that, but it is.

Cougar4 · 03-18-2013, 08:54 PM

Something doesn't seem right to me with the voltages you say are present while cranking. If the ignition system was really running at 3 volts I doubt it could function properly along with a number of other things. Perhaps you ground reference has a problem. Some things do get cut off from power while in the START mode but the ignition shouldn't. Installing a relay may not help either. I don't think it will turn on with only 3 volts going to the coil.

salvi · 03-18-2013, 10:54 PM

The voltage on the Ignition wire only drops when cranking, then returns to normal.

Cougar4 · 03-19-2013, 03:20 AM

As was mentioned earlier, some things get cut off from power when in the START mode and I suspect that is what you are seeing. Even though a circuit is marked 'Ignition' I can't see how the ignition system could function at that low of voltage you are seeing. Something doesn't sound right here. Perhaps you have a faulty ignition switch. One thing you could try in finding a good power source is to use the ohmmeter function of your meter. Disconnect the positive battery cable and connect one of the meter probes to the disconnected cable. Then while you turn the key to the START position probe the fuses in the dash and see if you can find any that show close to zero ohms which would indicate a connection to power. If you find one make sure there is the same reading in the ON position of the key.

03-04-2013, 01:19 PM	#1
herairk Scooby Newbie Member#: 346050 Join Date: Feb 2013 Location: Bermuda Dunes Vehicle: 2013 Wrx Pearl White	2013 gauge wiring question. http://www.wrxforums.com/forums/11-d...ost-gauge.html I followed this guide to fuse block tapping using same taps. My problem is my aem boost gauge is sweeping on the on positions but when cranking it sweeps again and sometimes shows incorrect reading. I think im losing power during crank, and throwing off the gauge. Is there a constant 12v that doesn't lose power while cranking in the fuse block? I really don't want to run a wire straight from battery, or tap the stock wiring anywhere if i don't have to. Thank in advance. Edit. I used a multimeter and tried to find a constant but either my meter is broken or there is none. I don't know. * Registered users of the site do not see these ads.

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03-04-2013, 04:14 PM	#2
Cougar4 Scooby Specialist Member#: 53443 Join Date: Jan 2004 Location: Anchorage, AK Vehicle: 2001 LL Bean Outback Winestone	To check your meter out simply use it to test the battery voltage and see if it works ok there. Most likely the meter is okay. Make sure you are set up to read DC volts with it. Most of the dash fuses have no power on them until the ignition switch is turned ON. There are a few like the door lock fuse that should have constant power since they need to provide power without the ignition being on. A lot of fused circuits are also tuned off while the key is in the START position while power is provided to the starter. This shouldn't affect the gauges though unless there is a connection problem but it will make them reset. To check the voltage at the fuses place the meter probe in the small slit located on top of the fuse. Also, it would be wise to purchase fuse taps if you wire directly into the fuse positions. By providing power directly to the gauges and not though the ignition switch it may cause a current draw on the battery you don't want to have.

03-04-2013, 07:53 PM	#4
Cougar4 Scooby Specialist Member#: 53443 Join Date: Jan 2004 Location: Anchorage, AK Vehicle: 2001 LL Bean Outback Winestone	Just because the meter is old it doesn't mean you can't trust it. Get a test light probe to do the testing if you don't believe your meter display. I assume you have an analog meter scale here. I would guess the door lock fuse power doesn't get cutoff with the ignition switch in the START position.

03-04-2013, 07:57 PM	#5
dirrtydetroit Scooby Newbie Member#: 295302 Join Date: Sep 2011 Location: East Cincy, OH Vehicle: 2005 RS Wagon PSM	Here's one to think on, what about the ECM fuse? Shouldn't that have power with ACC and START?

03-05-2013, 03:08 PM	#7
herairk Scooby Newbie Member#: 346050 Join Date: Feb 2013 Location: Bermuda Dunes Vehicle: 2013 Wrx Pearl White	update tried and tested every fuse in the interior fuse box. every single one cuts out during starting. If anyone has a aem analog face digital boost gauge on there 08+ please share your wiring and if you have experience the same problem.

03-06-2013, 12:34 PM	#9
herairk Scooby Newbie Member#: 346050 Join Date: Feb 2013 Location: Bermuda Dunes Vehicle: 2013 Wrx Pearl White	OK ANOTHER UPDATE. I kept playing with my meter and fuses, and it turns out my constant power 12v that was hooked up to the door lock fuse was good. It was my switched 12v that was cutting in and out causing the gauge to freak. I used the Turn Ignition fuse for the switched 12v and all is good! Just remember before cranking let the the gauge self zero then crank. Dont rush to crank without priming and letting the gauge zero it will not read right.

03-06-2013, 01:00 PM	#10
Cougar4 Scooby Specialist Member#: 53443 Join Date: Jan 2004 Location: Anchorage, AK Vehicle: 2001 LL Bean Outback Winestone	Glad you got it fixed. I guess the interrupted power was causing a problem since it appears that the gauge may be doing a calibration sequence during that time power got interrupted.

03-06-2013, 07:25 PM	#12
salvi Scooby Newbie Member#: 188132 Join Date: Aug 2008	I'm having the same issue on my aem gauge. If both your constant and switched power is not cutting out, the gauge should work fine even if you don't wait for it to calibrate.

03-07-2013, 01:06 AM	#14
salvi Scooby Newbie Member#: 188132 Join Date: Aug 2008	right, but if it loses power again when the car is turned on, the gauge will not finish zeroing correctly.

03-17-2013, 05:53 PM	#15
salvi Scooby Newbie Member#: 188132 Join Date: Aug 2008	Did more troubleshooting with my volt meter today. I've had the gauge off for a couple of days, but the wiring is still in place. All the wire connections are secured and reading properly. This is what I've found. 1. Ignition on Acc = Gauge will turn on and calibrate. Reads 12+ volts. Turn the car on from that position and 90% of time it will be fine. 2. Ignition to On= Gauge will turn on and calibrate. Reads 11.7 volts. Turn the car on from that position and 99% of time it will be fine. 3. Crank car from the start= Gauge will turn on and attempt to calibrate, but will stop at 0, the gauge reads inproperly. So I don't know why the gauge will not calibrate properly if you turn on the car normally. What I do notice from my voltmeter is that when going from Acc to On the constant power line drops from 12v to about 11.7. When going form the On to cranking, it will drop all the way to 10v, but recover back. The same thing happens with the Ignition wire, but the drop going from On to cranking is much severe. It will drop all the way to 4 volts. I wonder if the gauge needs to have a constant flow of power in order for it to calibrate properly and the low voltage during cranking is making it act weird like this. I've had many gauges, including the Autometer ones, and I've never had issues like these before. Is there any wire on the car that is an Ignition wire but doesn't drop so much current when the car is being cranked over? I'm going to look around all the plugs to see if I can find any.

03-17-2013, 06:31 PM	#16
salvi Scooby Newbie Member#: 188132 Join Date: Aug 2008	Ok, did some more testing right now. To verify that the issue is caused by extreme drop in voltage on the ignition wire during direct cranking without waiting for the gauge to calibrate, I connected the ignition wire direct to constant power. I only connected the wire to constant power right when I went to crank the car over. The issue doesn't occur when connected to constant power and I'm thinking that it's because the constant power source doesn't drop so much in current like the ignition source while cranking. Another thing I noticed is that the gauge will not calibrate when connected this way when you crank it directly. It will turn on and immediately read vacuum. I wonder if this is the correct operation of the gauge, maybe it only goes through the entire calibration process if you don't turn on the car fully and it's not ready vacuum from the sensor. I can probably leave the gauge connected this way using a relay that will only give power to the ignition wire when the key is on the Acc power, but will kill that wire when the key is Off. This way you don't have to wait for the gauge to calibrate every time you go to start the car, you can just turn on the car without any worries. I will setup the gauge like this as a last resort if I don't find a proper ignition wire that doesn't drop so much current while cranking.

03-17-2013, 09:01 PM	#17
Cougar4 Scooby Specialist Member#: 53443 Join Date: Jan 2004 Location: Anchorage, AK Vehicle: 2001 LL Bean Outback Winestone	The battery voltage drops to around 10 volts in the START mode due to the heavy current load of starter motor, that is normal. The 4 volt ignition source isn't what it should be though. It should be close to the battery voltage. There may be some dirty contacts in the ignition switch. You could check the input to the switch and see if that is ok. You don't want to tie power directly to the gauge as that will cause a drain on the battery. You will need to add a relay to get the power to the gauge.

03-17-2013, 11:31 PM	#18
salvi Scooby Newbie Member#: 188132 Join Date: Aug 2008	All the Ignition sources drop to 3-4 Volts when the car is cranking over, not one source that I tested doesn't drop. I'm going to connect the gauge to constant power with a relay as stated earlier. It will have constant power, but it will be switched as well. The Ignition power drops, but comes back to normal after startup and this is what I think the gauge is not liking. I don't know why this gauge is like that, but it is.

03-18-2013, 08:54 PM	#19
Cougar4 Scooby Specialist Member#: 53443 Join Date: Jan 2004 Location: Anchorage, AK Vehicle: 2001 LL Bean Outback Winestone	Something doesn't seem right to me with the voltages you say are present while cranking. If the ignition system was really running at 3 volts I doubt it could function properly along with a number of other things. Perhaps you ground reference has a problem. Some things do get cut off from power while in the START mode but the ignition shouldn't. Installing a relay may not help either. I don't think it will turn on with only 3 volts going to the coil.

03-18-2013, 10:54 PM	#20
salvi Scooby Newbie Member#: 188132 Join Date: Aug 2008	The voltage on the Ignition wire only drops when cranking, then returns to normal.

03-19-2013, 03:20 AM	#21
Cougar4 Scooby Specialist Member#: 53443 Join Date: Jan 2004 Location: Anchorage, AK Vehicle: 2001 LL Bean Outback Winestone	As was mentioned earlier, some things get cut off from power when in the START mode and I suspect that is what you are seeing. Even though a circuit is marked 'Ignition' I can't see how the ignition system could function at that low of voltage you are seeing. Something doesn't sound right here. Perhaps you have a faulty ignition switch. One thing you could try in finding a good power source is to use the ohmmeter function of your meter. Disconnect the positive battery cable and connect one of the meter probes to the disconnected cable. Then while you turn the key to the START position probe the fuses in the dash and see if you can find any that show close to zero ohms which would indicate a connection to power. If you find one make sure there is the same reading in the ON position of the key.