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S13 Body Harness Pinout

Dash Connector, 15-pin white plug next to the ECU

1 – Blue/Black – Thermal Transmitter for OEM coolant temp gauge

2 – Yellow/Red – Tach signal for OEM tach

3 – Yellow/Green – Vehicle Speed Sensor (VSS) signal from speedometer

4 – Blue/Green – Thermistor Control Amplifier

10 – Orange – Start Signal, connect to start signal from ignition switch

11 - Green – Transmit (TX) pin for CONSULT

12 – Green/Black – Receive (RX) pin for CONSULT

13 – Green/Yellow – ?

14 - Green/White – Clock (CLK) synchronization pin for CONSULT

15 – Red – MIL Check Engine Light

17 – Black – ground for CONSULT

18 - Green/Red – Clock signal for CONSULT

? – Red/White – Fuel Pressure Control Module

? – Orange/Black – exhaust temp warning lamp

? – Blue/White - Intake Air Temperature Sensor

Misc SR20DET A/C Info

Links used for reference

http://www.freshalloy.com/showthread.php/143199-Wire-colors-240sx-KA24DE-F3-Plug-identification-pros

http://www.nicoclub.com/articles/images/KA-ecu-pinout-1.gif

http://forums.nicoclub.com/what-are-the-benefits-of-using-s14-f3-plug-as-opposed-to-repinning-r33-f3-plug-t397665.html

http://www.frsport.com/SR20DET-Swap-Engine-Harness-Wiring-Diagram-Guide-SR-SR20_t_26.html

http://www.nicoclub.com/articles/images/interiortable.gif

http://zilvia.net/f/showthread.php?t=290700

http://forums.ma240sx.net/showthread.php?tid=8421

Misc Info

“A/C for the SR in an s13 can use two compressors– KA24DE (so you dont have to open up the system and recharge, and you can only use the front two compressor bracket bolts)

or SR ( bolts perfectly to bracket (duh) but needs large line modified and a/c recharged.

as for the wiring, wire the SR motor as its always done, but there is a difference in the way USDM and JDM a/c compressor clutch signal is routed.

in the USDM s13, the a/c clutch wire (blue/grn stripe) comes from the body harness, where as in the JDM S13, it comes off the ECCS harness.

the way you make it work, is to install the sr, hook up compressor, and hook up the blue green single spade connector hanging off the frame rail (as it is part of the engine bay body harness, its not going anywhere)

Now, in the SR harness, the battery tray area plugs has a big grey 8 pin connector, just make sure the blue/grn wire goes to the blue/grn wire on the car side of the plug connection (F8 i beleive, just off the top of my head)

also, make sure the green/yellow wire from the grey plug, makes it over to the car side brown plug (the wire is located on a different plug so just swap the wire over

then, at the blue ECU plug, pin 41 goes to the white underdash plug, make sure that the blue/grn wire running from pin 41 going to the white underdash plug makes connection with the blue/grn underdash wire (that is the a/c on signal from your HVAC control panel.

basically this is what happens when your driving your SR and you hit the “A/C” button:
—————————–

signal from HVAC control panel to pin 41 on ecu, tells ecu to kick up idle, simultaneously, ecu sends signal along green/yellow wire to the a/c relay — kicking it on, which sends power to the blue/grn wire running in the body harness to the a/c compressor clutch, activating the clutch and making the compressor work.”   ———————————– AC wiring for s13 into s14.. Easy way.. Go to F3 plug and wire in black/pink (not the fuel pump lead) to yellow w/black. The black w/ pink once it receives a ground will kick AC relay on. The yellow w/black becomes a ground once you hit the AC button. This like Taylor said is a ok way of doing it. The reason why AC signal goes into the ECU and out to the body harness is because the ECU decides weather or not it will let you kick it on… again like Taylor said… WOT.. and there are some others.. engine temp over 188 F or RPM above i think 5500. The relay gimmick is the more proper way of doing it. Since a S13 ECU receives and puts out a 12V signal rather than a ground to trigger the AC relay, you need to take the F3 yellow w/ black wire and supply it as a trigger to a relay that will supply 12V into the S13 ECU AC input. Then take the 12V S13 ECU AC out (both these are blue/green) and use it as a trigger for a second relay. This relay will swith a ground though which will feed the black w/ pink on the F3 plug to actually trigger the AC relay in the relay box. If you do it the first way you will need to also tap into the AC wire going to your compressor and send this over to your Idle Air Controller Valve (tap the blue /green wire going to it. The second way actually does it for you because the blue/gree out coming out of the ECU branches and goes directly to that. Now you have functioning AC and a good idle :D I made a quick sketch… I will update it tomorrow with pin numbers. Class dismissed.

Misc Pinouts

Dash Connector, 15-pin white plug next to the ECU

1 – Blue/Black – Thermal Transmitter for OEM coolant temp gauge

2 – Yellow/Red – Tach signal for OEM tach

3 – Yellow/Green – Vehicle Speed Sensor (VSS) signal from speedometer

4 – Blue/Green – Thermistor Control Amplifier

10 – Orange – Start Signal, connect to start signal from ignition switch

11 - Green – Transmit (TX) pin for CONSULT

12 – Green/Black – Receive (RX) pin for CONSULT

13 – Green/Yellow – ?

14 - Green/White – Clock (CLK) synchronization pin for CONSULT

15 – Red – MIL Check Engine Light

17 – Black – ground for CONSULT

18 - Green/Red – Clock signal for CONSULT

? – Red/White – Fuel Pressure Control Module

? – Orange/Black – exhaust temp warning lamp

? – Blue/White - Intake Air Temperature Sensor



ECU plug:

Large 64-pin connector:
1 – Coil Pack 1 Output (Via power transistor Unit) – Red White, connect to pin 1 of ignitor chip
2 – Coil Pack 2 Output (Via power transistor Unit) – Red Yellow, connect to pin 2 of ignitor chip
3 – Tachometer signal output – Yellow Red, not needed
4 – ECCS Relay – Red Black, connect to ground pin of ECCS relay
5 – Ignition Pulse Monitor (IT monitor, For Trip Comp ?), not needed
6 – Ignition Signal Ground – Black, connect to ground
7 – RX data (Signal from Nissan Consult hand terminal) -Green Black, not needed
8 – Coil Pack 3 Output (Via power transistor Unit) – Red White, connect to pin 4 of ignitor chip
9 – Coil Pack 4 Output (Via power transistor Unit) – Red White, connect to pin 5 of ignitor chip
10 -
11 -
12 – A/T autotrans gear select – Pink Black, not needed
13 – Ignition Signal Ground – Black, connect to ground
14 – CLK clock (timing signal) – Green White, not needed
15 – TX data (signal to Nissan Consult hand terminal) – Green, not needed
16 – MAFS signal input ( Mass Air Flow Sensor ) – White, connect to signal pin of MAFS
17 – MAFS ground – Black, connect to ground pin of MAFS
18 – Water Temp Sensor input – Blue Brown, connect to positive terminal of 2-pin coolant temperature sensor
19 – Oxygen Sensor input (O2) – White, connect to middle signal pin of O2 sensor
20 – TPS input (throttle postion sensor) – White, connect to signal pin of TPS
21 – Sensor ground – Black, connect to ground
22 – CAS 180deg signal (Crank angle sensor) – White, connect to pin 1 of CAS
23 – CLK for CONSULT - Green Red, not needed
24 – Monitor check Lamp (red) (fault code lamp output), not needed
25 – Exhaust over temp warning lamp output – Orange, not needed
26 – Exhaust temp sensor (Behind the Cat) – Blue Yellow, not needed
27 – Detonation sensorinput (knock sensor) – White, connect to knock sensor
28 – TPS for A/T (kick down switch), not needed
29 – Sensor ground – Black, connect to ground
30 – CAS 180deg signal (crank angle sensor) – White, connect to pin 1 of CAS
31 – CAS 1deg signal (crank angle sensor) – Black, connect to pin 2 of CAS
32 – Speed sensor input – Yellow Green, not needed
33 -
34 – Start signal (from ignition switch) – Orange, connect to start signal from ignition switch
35 – A/T neutral switch input – Green Orange, not needed
36 – IGN (ignition ON, from ignition switch) – Black Red, connect to switched ignition power
37 – TPS power output (power to throttle position sensor) – Light Green Red, connect to pin 3 of TPS
38 – ECCS power – Black White, connect to power output pin of ECCS relay
39 – ECCS ground – Black, connect to ground
40 – CAS 1 deg signal (crank angle sensor) – Red Black, connect to pin 2 of CAS
41 – A/C on input (Air Con ON from A/C panel) – Blue Green, not needed
42 – A/T signal DT1 (auto trans gear select), not needed
43 - Power steering switch (speed proportional control output) – Purple White, not needed
44 – A/T signal DT1 (auto trans gear select), not needed
45 – Ambient air temp sensor input – Blue White, not needed
46 – ECCS backup power – Red, connect to constant power
47 – ECCS power – Black White, connect to power output pin of ECCS relay
48 – ECCS ground – Black, connect to ground
101 – Injector No. 1 drive output – White Black, connect to pin 2 of #1 injector
102 – EAI control solenoid output (egr valve control) – Orange Black, not needed
103 – Injector No.3 drive output – Green Black, connect to pin 2 of #3 injector
104 – Fuel pump relay output – Black/Pink, connect to ground pin of fuel pump relay
105 – Fuel pressure control module – Red White, not needed
106 – A/C on output (Air conditioner on relay signal) – Green Black, not needed
107 – Injector ground – Black, connect to ground
108 – Injector ground – Black, connect to ground
109 – Reverse electrical flow return circuit (alternator fail input) – Red, connect to constant power
110 – Injector No. 2 drive output – Yellow Black, connect to pin 2 of #2 injector
111 – Turbo boost pressure control solenoid (over boost cut ?) – Orange Black, not needed
112 – Injector No. 4 drive output – Blue Black, connect to pin 2 of #4 injector
113 - AAC valve control (Auxiliary Air Control, Idle speed control) – Light Blue, connect to pin 3 of AAC/FICD subharness
114 -
115 -
116 – Injector ground – Black, connect to ground

O2 Sensor Plug, connect to O2 sensor
1 – Brown, Power for heating element, connect to switched power
2 – White, Signal, connect to pin 19 of ECU and the shielded wire to ground
3 – Black , Ground, connect to ground

Coil pack harness – 5 pins, 2 rows x 3 pins per row, 1 pin blank, grey, connect to coil pack subharness
Blue/Red – coil pack power, connect to switched power
Red/Green – #4 coil signal, connect to pin A of ignitor chip
Red – #3 coil signal, connect to pin B of ignitor chip
Red/White – #2 coil signal, connect to pin C of ignitor chip
Red/Blue – #1 coil signal, connect to pin D of ignitor chip

Ground Terminals - connect to suitable chassis grounds

Injector #1, connect to #1 injector
1 – Red, power, connect to switched power
2 – White/Black, #1 injector signal, connect to pin 101 of ECU

Injector #2, connect to #2 injector
1 – Red, power, connect to switched power
2 – Yellow/Black, #2 injector signal, connect to pin 110 of ECU

Injector #3, connect to #3 injector
1 – Red, power, connect to switched power
2 – Green/Black, #3 injector signal, connect to pin 103 of ECU

Injector #4, connect to #4 injector
1 – Red, power, connect to switched power
2 – Blue/Black, #4 injector signal, connect to pin 112 of ECU

AAC valve and FICD – 4 pins, 2 pins per row X 2 rows, connect to the idle control system subharness, the FICD pins are for the AC and are not needed
1 – Blue/Red, FICD ground, goes to the Small Grey Plug, not needed
2 – Blue/Green, FICD power from AC relay, from the Small Grey Plug, not needed
3 – Sky Blue, AAC valve ground, connect to pin 113 of ECU
4 – Black/Yellow, AAC valve power, connect to switched power at the Big Grey Plug

Detonation Sensor – 2 pin, grey, connect to the knock sensor
1 – White, knock sensor signal, connect to pin 27 of ECU
2 – Black, ground, connect to ground

Coolant Temp Connector – connect to coolant temp subharness
Blue/Orange – sensor signal for coolant temp, pin 18 of ECU
Black – sensor ground, connect to ground
Blue/Black – thermal transmitter, not needed

Coolant Temperature Sensor – connect to coolant temp sensor
Blue/Orange – sensor signal for coolant temp, pin 18 of ECU
Black – sensor ground, connect to ground

Thermal Transmitter – not needed
Red – thermal transmitter, not needed

Throttle Position Sensor – connect to TPS
1 – Light Green/Red, TPS power, connect to pin 37 of ECU
2 – White, TPS signal, connect to pin 20 of ECU
3 – Black, sensor ground, connect to ground

Cam Angle Sensor - connect to CAS but DO NOT CONNECT TO IGNITOR CHIP BY ACCIDENT. These connectors are the same and will interchange if not careful.
1 – Thick White, CAS 180 degree signal, connect to pins 22, 30 and ground
2 – Thick Black, CAS 1 degree signal, connect to pins 31, 40 and ground
3 – Black/White, CAS power, connect to switched power
4 – Black, ground, connect to ground

Ignitor chip – connect to ignitor chip
1 – Red/White, #1 coil signal, connect to pin 1 of ECU
2 – Red/Yellow, #2 coil signal, connect to pin 2 of ECU
3 – Black, ground, connect to ground
4 – Red/Green, #3 coil signal, connect to pin 8 of ECU
5 – Red/Blue, #4 coil signal, connect to pin 9 of ECU
A – Red/Green – #4 coil signal, connect to coil pack subharness
B – Red – #3 coil signal, connect to coil pack subharness
C – Red/White – #2 coil signal, connect to coil pack subharness
D – Red/Blue – #1 coil signal, connect to coil pack subharness

Turbo Boost Pressure Solenoid, 2-pin, black plug, not needed
1 – Brown, power, connected to Brown Plug, not needed
2 – Orange/Black, solenoid activation signal controlled by pin 111 of ECU, not needed

EAI EGR, 2 pin, not needed
1 – Orange/Blue, activation signal controlled by pin 102 of ECU, not needed
2 – Brown, switched power, connected to Brown Plug, not needed

Power Steering Switch, 2 pin, black, not needed
Purple/White – switch power controlled by pin 43 of ECU, not needed
Black – ground, not needed

AC compressor, 1 pin, white, not needed
Blue/Green – power from the AC relay, not needed

MAFS, 4 pin, 1 pin blank, black
1 – White, MAF signal, connect to pin 16 of ECU
2 – Black, MAF ground, connect to pin 17 of ECU and ground
3 – Unknown colour, power, connect to switched power

Intake Air Temperature Sensor, 2 pin, black, not needed
Blue/White - Intake Air Temp Sensor connected to dash plug, not needed
Black – ground, not needed

#1 Coil Check Connector, 1 pin, grey cylindrical, not needed
Red – #1 coil signal connected to check resistor, not needed

Tach Check connector, 1 pin, grey cylindrical, not needed
Yellow/Red – tach signal on pin 3 of ECU, not needed

#1 Coil Check Connector Resistor, 2 pin, brown plug, not needed
Red/Blue – #1 coil signal from ignitor chip, not needed
Red – check connector, not needed

Brown Plug, 8 pin, 3 pins empty, cut and rewire as necessary
Red/Black – ECU relay ground pin controlled by pin 4 of ECU, connect to ground pin of ECU relay
Brown – Power source for all sensors, connect to switched power
Green/Yellow – AC relay, not needed
Black/Pink – fuel pump relay ground pin controlled by pin 104 of ECU, connect to ground pin of fuel pump relay
Green/Orange – park/neutral position to pin 35, not needed

Small Grey Plug, 6 pin, 2 pins empty, not needed
Black – ground, not needed
Blue/Yellow – exhaust temp sensor signal to pin 26 of ECU, not needed
Blue/Green – AC power, not needed
Blue/Red – FICD ground, not needed

Big Grey Plug, 8 pin, 2 pins empty, cut off and rewire as needed
Blue/Red – coil pack power, connect to switched power
Black/Red – ingition power, connect to switched power
Blue/Yellow – AAC valve power, connect to switched power
Black/White – ECU power to pin 47 and 38 of ECU, connect to switched power
Blue/Green – power from the AC relay, power goes to the AC compressor and the FICD, not needed
Red – ECU Backup power to pins 46 and 109 of ECU, connect to constant power

S13 SR20DET ECU Pinout

nissan_sr20det_1991_1995

1 Red/White Coil Pack 1 Output, connect to pin 1 of ignitor chip
2 Red/Yellow Coil Pack 2 Output, connect to pin 2 of ignitor chip
3 Yellow/Red Tachometer signal output, connect to tachometer
4 Red/Black ECCS Relay Ground, connect to ground pin of ECCS relay
5 ? Injector Pressure TI Monitor
6 Black Ignition Signal Ground, connect to ground
7 Green/Black CONSULT RX (Receive)
8 Red/White Coil Pack 3 Output, connect to pin 4 of ignitor chip
9 Red/White Coil Pack 4 Output, connect to pin 5 of ignitor chip
10 - 
11 -
12 Pink/Black A/T gear select
13 Black Ignition Signal Ground, connect to ground
14 Green/White CONSULT CLK (Clock)
15 Green CONSULT TX (Transmit)
16 White MAFS signal, connect to signal pin of MAFS
17 Black MAFS ground, connect to ground pin of MAFS
18 Blue/Brown Water Temp Sensor input, connect to positive terminal of 2-pin coolant temperature sensor
19 White O2 Sensor signal, connect to middle signal pin of O2 sensor
20 White TPS signal, connect to signal pin of TPS
21 Black Sensor ground, connect to ground
22 White CAS 180deg signal, connect to pin 1 of CAS
23 Green/Red CONSULT CHK (Check)
24 Red Check Engine Lamp (red), connect to ground pin of light bulb
25 Orange Exhaust temp warning lamp, connect to ground pin of light bulb 
26 Blue/Yellow Exhaust temp sensor
27 White Detonation/Knock Sensor signal, connect to knock sensor
28 ? TPS kickdown switch for A/T
29 Black Sensor ground, connect to ground
30 White CAS 180deg signal, connect to pin 1 of CAS
31 Black CAS 1deg signal, connect to pin 2 of CAS
32 Yellow/Green Speed sensor input, connect to S13 speedometer
33 - 
34 Orange Start enrichment, connect to start signal from ignition switch
35 Green/Orange A/T neutral switch
36 Black/Red Switch ignition power ON/ST, connect to ignition switch
37 Light Green/Red TPS power, connect to pin 3 of TPS
38 Black/White ECCS power, connect to power output pin of ECCS relay
39 Black ECCS ground, connect to ground
40 Red/Black CAS 1 deg signal, connect to pin 2 of CAS
41 Blue/Green A/C switch
42 ? A/T signal DT1 (auto trans gear select)
43 Purple/White Power steering pressure switch
44 ? A/T signal DT1 (auto trans gear select)
45 Blue/White Ambient air temp sensor signal
46 Red ECCS backup power, connect to constant power
47 Black/White ECCS power, connect to power output pin of ECCS relay
48 Black ECCS ground, connect to ground
101 White/Black Injector 1, connect to pin 2 of #1 injector
102 Orange/Black EAI (Exhaust Air Injection) control solenoid 
103 Green/Black Injector 3, connect to pin 2 of #3 injector
104 Black/Pink Fuel pump relay, connect to ground pin of fuel pump relay
105 Red/White Fuel pressure control module
106 Green/Black A/C compressor power
107 Black Injector ground, connect to ground
108 Black Injector ground, connect to ground
109 Red Reverse electrical flow return circuit (alternator fail input), connect to constant power
110 Yellow/Black Injector 2, connect to pin 2 of #2 injector
111 Orange/Black Turbo boost pressure control solenoid
112 Blue/Black Injector 4, connect to pin 2 of #4 injector
113 Light Blue AAC valve signal (Auxiliary Air Control), connect to pin 3 of AAC/FICD subharness
114 -
115 -
116 Black Injector ground, connect to ground

SR20DET A/C Wiring in S13

I’ll be collecting my notes on wiring AC that has been installed on an SR20DET in my S13 (1990).

My Setup…

  • SR20DET Red Top
  • A/C Lines – S13 DOHC
  • A/C Compressor – S13 DOHC
  • A/C Condensor – S13 DOHC
  • A/C Evaporator Core – S13 DOHC

Condensor Fan & Idle Bump Wiring

When the A/C is on, your ecu needs to bump up the idle to compensate for the extra load.

S13/S14 Body Harness Pins (may have to be translated to S13 colors)

  • 16 (yellow/black) –  A/C Switch
  • 46 (black/pink) – Tripple Pressure Switch (Thermo Control Amp)
  • One of the blue/green from S13 harness? - Thermo Control Amp?
  • 41 (KA F3) (blue/green) – Cooling Fan Low Signal
  • 25 (KA F3) (orange/blue) – Cooling Fan High Signal

S13 SR20DET ECU Harness

  • 41 (blue/green) – A/C on Input (Air Cond On from A/C Panel)

Fans & Idle

This will get the ecu to turn on AC mode, kick up the IACV and turn on the AC fan.

  • Connect pin 16 (yellow/ black from Body Harness) to pin 46 (black/pink from Body Harness) and pin 41 (blue/green from ECU Harness).
  • Connect pin 41 and/or pin 25 to one of the blue/green from the S13 harness. (this gets the fan to run on LOW/HIGH)

” on the f3 conector (big white plug under dashboard near passenger foot well , you know the one you have to splice into to make your engine swap work) you need to splice together the following cables pin 16 yellow/ black to pin 43 or 46 (cant remeber now im at work) black/pink. and what do you know voila it works, push the a/c button a/c turns on, pust it again it turns off.”

This is what I did, except I spliced in the wires for the IACV and the hi/lo fan. This us using the KA compressor.

MAF Testing & Cleaning

This is intended for 1998-1994 240SX

“Avoid using solvents that leave residues: like the aromatics [toluene, xylene]. Use electrical parts cleaner or Windex and a Q-tip to gently scrub the wires clean. Acetone, methelyene chloride or chloroform will also work well. (NOTE: It has been said that carburetor cleaner is too harsh to use).

Note: The Q-tip method is recommended only when the sensor wires are really dirty and simply spraying cleaner on them will not clean them. Be very careful when using a Q-tip! Use a Q-tip and gently scrub the wires.

If the MAF wires are not really dirty you shouldn’t need to use a Q-tip. Just spray the wires and let dry. If there is still gunk on them – use a q-tip to clean them. If you break a wire you are screwed. Do NOT scrape with anything. ” by Rogoman

MAF testing

(for the proceeding test , the maf is connected to ecu so you have to pull back rubber part at connector and insert tester probe)
1.Warm engine
2. with engine off and ignition in ON position, test between terminal 1
and ground . should read .2 volts
3.with engine on at idle, it should be 1-1.4 volts

There are 4 terminals on the plug 4 3 2 1
—————————————————————————–


Another thing thats really important here is check that ground on your MAF make sure it is under .2 volts drop to ground

Testing Grounds – Voltage Drop Test

start the engine.. turn on the headlights…

set digital volt meter to 20 volts DC..

1.  measure from the positive battery POST to the negative battery post..  14.1 to 14.8 volts is expected.

2. measure from the Negative battery post to the engine block…              0.04 volts is expected..

3. measure from the negative battery post to the body……………………  0.02 volts is expected.

4. measure from the ENGINE BLOCK to the BODY …………………………. 0.02 volts is expected..

if you get 0.00 on test 2, 3, 4.. change the meter setting to 2 volts DC and retest 2, 3, 4..

if you get more than the 0.04 or 0.02 volts…  you have a bad ground between those parts.. a little over can be do to an undersized ground wire..

this test takes about 2 minutes to do.. including the time it takes to get the volt meter out..   it will find all the gremlins.. save your hours of work chasing ghosts..

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

why spend this two minutes..   to avoid come backs..  to avoid hours of trouble shooting that gets you nowhere..

the reason behind it..

electrons flow from negative to positive.. 

the engine is normally mounted on rubber mounts.. so its not really attached to the body except via ground wires…

electrons take the shortest path …

there should be at least 3 ground wires on every car…

battery negative to the engine block.. this is a battery cable usually 4 or 6 gauge…..

battery negative to the body of the car..  this is thinner.. usually 8 or 10 gauge..

engine block to the body.. usually at the firewall…   this is also usually 8 to 12 gauge..  usually braided so its flexible.. but not always..

if you don’t have a good ground between the various parts..  when loads are applied..  there may not be enough electrons flowing through the ground connection to power the circuit..

copper wire has some resistance in it to electron flow…

your digital volt meter will read the difference in voltage between where you test at..  if there is a load on the circuit being tested..  you can with your digital volt meter.. measure the ends of the circuit and any difference in voltage will be displayed..  this helps you as if you get the 0.04 or 0.02 volts you know the circuit is working properly  as there is a tiny amount of voltage drop…  if you get 0.00.. change the meter setting to a 2 volts DC scale and retest..

but why…

if there is a problem with the ground circuit.. you are going to get more than the 0.04 or 0.02 volts..  i got 8.5 volts on one chevy  truck between the engine and the body.. cleaned the various ground connections. and fixed many of the problems..

why test the battery voltage..  if you don’t get the 14.1 to 14.8  you know you have a positive side problem.. or an charging system problem..

Source - http://workshop.search-autoparts.com