ground offset issues w/ LC1
Thread Starter
Joined: May 2004
Posts: 1,080
Likes: 0
From: Elgin, Illinois
ground offset issues w/ LC1 Well i set my lc1 output to a linear .5V and this is what im getting. Its all over the place. At 5.0V I get a steady 4.917V w/ an occasional switch to 4.922V but .5 V is all over the board as is 2.45V. Anyone have any ideas? This POS is frustrating me.. This is in a c5 vette FWIW.
Raw Voltage V
0.522
0.601
0.64
0.547
0.522
0.63
0.679
0.591
0.63
0.625
0.654
0.527
0.596
0.688
0.581
0.605
0.684
0.728
0.664
0.566
0.654
0.684
0.747
0.557
0.693
0.742
0.732
0.625
0.698
0.62
0.557
0.601
0.664
0.615
0.61
0.64
0.718
0.688
0.61
0.654
0.571
0.518
0.659
0.635
0.645
0.552
0.635
0.645
0.552
0.62
0.693
0.605
0.547
0.635
0.732
0.615
0.586
0.61
0.664
0.649
0.532
0.771
0.659
0.518
0.62
0.63
0.605
0.562
0.635
0.742
0.64
0.63
0.605
0.635
0.557
0.591
0.693
0.645
0.488
0.625
0.64
0.63
0.562
0.693
0.601
0.62
0.591
0.703
0.669
0.513
0.601
0.62
0.62
0.547
0.61
0.679
0.684
0.547
0.742
0.703
0.62
0.576
0.664
0.64
0.62
0.625
0.596
0.537
0.532
0.723
0.693
0.576
0.596
0.654
0.552
0.537
0.615
0.674
0.601
0.557
0.703
0.664
0.566
0.586
0.669
0.571
0.664
0.625
0.713
0.698
0.586
0.645
0.684
0.591
0.552
0.62
0.596
0.586
0.635
0.664
0.605
0.557
0.591
0.635
0.659
0.615
0.645
0.654
0.586
0.645
0.679
0.635
0.571
0.596
0.732
0.581
0.557
0.635
0.61
0.61
0.527
0.713
0.63
0.552
0.601
0.659
0.571
0.513
0.654
0.635
0.591
0.586
0.596
0.698
0.527
0.527
0.723
0.615
Raw Voltage V
0.522
0.601
0.64
0.547
0.522
0.63
0.679
0.591
0.63
0.625
0.654
0.527
0.596
0.688
0.581
0.605
0.684
0.728
0.664
0.566
0.654
0.684
0.747
0.557
0.693
0.742
0.732
0.625
0.698
0.62
0.557
0.601
0.664
0.615
0.61
0.64
0.718
0.688
0.61
0.654
0.571
0.518
0.659
0.635
0.645
0.552
0.635
0.645
0.552
0.62
0.693
0.605
0.547
0.635
0.732
0.615
0.586
0.61
0.664
0.649
0.532
0.771
0.659
0.518
0.62
0.63
0.605
0.562
0.635
0.742
0.64
0.63
0.605
0.635
0.557
0.591
0.693
0.645
0.488
0.625
0.64
0.63
0.562
0.693
0.601
0.62
0.591
0.703
0.669
0.513
0.601
0.62
0.62
0.547
0.61
0.679
0.684
0.547
0.742
0.703
0.62
0.576
0.664
0.64
0.62
0.625
0.596
0.537
0.532
0.723
0.693
0.576
0.596
0.654
0.552
0.537
0.615
0.674
0.601
0.557
0.703
0.664
0.566
0.586
0.669
0.571
0.664
0.625
0.713
0.698
0.586
0.645
0.684
0.591
0.552
0.62
0.596
0.586
0.635
0.664
0.605
0.557
0.591
0.635
0.659
0.615
0.645
0.654
0.586
0.645
0.679
0.635
0.571
0.596
0.732
0.581
0.557
0.635
0.61
0.61
0.527
0.713
0.63
0.552
0.601
0.659
0.571
0.513
0.654
0.635
0.591
0.586
0.596
0.698
0.527
0.527
0.723
0.615
Thread Starter
Joined: May 2004
Posts: 1,080
Likes: 0
From: Elgin, Illinois
Its a vette so I have very few to get at. I took a ground off the ECM if I recall correctly. Do you think the problem lies in my wiring? It does this for all voltages EXCEPT 5V which is steady at 4.917V. And I have all 3 grounds going to the same spot too, I read this may not be a wise idea but its VERY hard to find a chassis ground on a plastic car lol.. After rereading the manual it says
"the blue, white and green wires should all be grounded to the same ground source and although these grounds are of the same source , the BLUE wire should be wired separately from the white and green wires to avoid analog noise."
WTF? wired together but separately?
Dave
"the blue, white and green wires should all be grounded to the same ground source and although these grounds are of the same source , the BLUE wire should be wired separately from the white and green wires to avoid analog noise."
WTF? wired together but separately?
Dave
Thread Starter
Joined: May 2004
Posts: 1,080
Likes: 0
From: Elgin, Illinois
how bout the batterY? it would be easier. Thats going to look like crap. YOu think thats the problem? A ground?? I guess i can text that theory and run a temp ground to neg of battery.
Dave
Dave
I have the LC-1 on my vette. Basically, I used the old O2 harness to wire up the WB. Then I ran the 0-5V DC signal wire from the WB to inside the car. I grounded the signal wire to the EIO of HPT. Also, the LED and calibration wire are connected to a ground near the radio.
In short, heater ground is separate from signal, which is also separate from calibration. BTW, I use the WB to simulate NB signal also...works great.
In short, heater ground is separate from signal, which is also separate from calibration. BTW, I use the WB to simulate NB signal also...works great.
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Thread Starter
Joined: May 2004
Posts: 1,080
Likes: 0
From: Elgin, Illinois
old o2 harness? I put a bung in. So you used a ground from the EIO to the signal wire? What wire is the "signal" wire? Do you have the other 2 grounds together at the radio?
Dave
Dave
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Verdad Gallardo If my memory serves me correctly, there are 4 grounds (if you use the NB simulation also) on the LC-1.
1) Heater- This I tapped from stock location (original wiring harness)
2) NB- This also is provided by the original harness.
3) Signal- (0-5V DC signal for HPT) this is grounded to the EIO
4) Calibration- mounted LED and push button in ashtray and connected ground near radio.
If you are using a bung, then you'll need switched 12VDC and engine ground (for the heater). Run the signal (positive and negative) from the LC-1 into the cabin and connect to EIO. Calibration is optional.
Best of Luck
1) Heater- This I tapped from stock location (original wiring harness)
2) NB- This also is provided by the original harness.
3) Signal- (0-5V DC signal for HPT) this is grounded to the EIO
4) Calibration- mounted LED and push button in ashtray and connected ground near radio.
If you are using a bung, then you'll need switched 12VDC and engine ground (for the heater). Run the signal (positive and negative) from the LC-1 into the cabin and connect to EIO. Calibration is optional.
Best of Luck
my lc1's didn't like drawing power or ground from the stock o2 sensor bungs (PCM supplied). I ended up running a direct connection to the battery for power and used the rear o2 power/ground to drive a relay for proper on/off switching for the lc1. LC1 ground is chassis ground.
I ran a ground directly from the batter/chassis ground to a terminal block behind the dash. Then I attached the autometer gauges, LC-1, etc. to individual terminals on the terminal block which has that nice SOLID 12 gauge? wire running to the same ground on the inner fender that the battery goes to. Seems to work well.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Originally Posted by TT_Vert
which one is signal negative? system or analog ground?
Originally Posted by joecar
Either one will work as signal ground.
Originally Posted by TT_Vert
you lost me now
Either analog ground (green) or system ground (white) can be used as the "signal negative"; they are internally connected;
this is how I connected mine (includes NBO2 simulation):
NBO2 connections:
NBO2 Signal Low (A) = LC-1 green (analog ground)
NBO2 Signal High (B) = LC-1 yellow (NB signal)
Heater Ground (C) = LC-1 blue (ground)
Heater Power (D) = LC-1 red (power)
Other connections:
FlashScan analog signal = LC-1 brown (WB signal)
FlashScan analog ground = LC-1 white (system ground)
LED/Pushbutton ground = LC-1 white (system ground)
LED/Pushbutton positive = LC-1 black (calibration)
Note:
System ground (white) is being used as the analog ground for the wideband signal,
and as the ground for the calibration pushbutton/LED.
NBO2 Signal Low (A) = LC-1 green (analog ground)
NBO2 Signal High (B) = LC-1 yellow (NB signal)
Heater Ground (C) = LC-1 blue (ground)
Heater Power (D) = LC-1 red (power)
Other connections:
FlashScan analog signal = LC-1 brown (WB signal)
FlashScan analog ground = LC-1 white (system ground)
LED/Pushbutton ground = LC-1 white (system ground)
LED/Pushbutton positive = LC-1 black (calibration)
Note:
System ground (white) is being used as the analog ground for the wideband signal,
and as the ground for the calibration pushbutton/LED.
from what i understand the engine block NOT the battery is the true ground of the car as the alternator is the reference point. run your grounds to the block with the blue wire attached seperately.
Originally Posted by svede1212
from what i understand the engine block NOT the battery is the true ground of the car as the alternator is the reference point. run your grounds to the block with the blue wire attached seperately.
__________________
Originally Posted by cantdrv65
The engine block and battery negative are electrically equal....they are connected together. You can look at them as the same point.
__________________
__________________
Originally Posted by GuitsBoy
Technically, even that short run of cable ground cable between the block and battery would have some resistance, and therefore create atleast some differential.
Last edited by cantdrv65; May 19, 2006 at 03:52 AM.
