1. Check that wires are correctly installed into DPU and have not broken or come loose. Inspect closely because a wire that has just broken may not be easy to detect. Give the wire a gentle pull to insure it is connected. Insure that wire is not touching adjacent wires or DPU case.

2. Repeat this inspection at the transducer end of the cable.

3. Measure continuity of each wire from transducer terminals to appropriate DPU terminal block screw. There should be very low resistance if the wire is intact. If resistance is greater that 0.7 ohms, then stop and correct connections.
Resistances =  (WHT) ________, (RED) ________, (BLK) ________.
4. Measure resistance between the WHT and BLK wires. (s/b approx  =  ohms) .  Resistance = ________

5. Measure resistance between the WHT and RED wires. (s/b approx =  ohms).  Resistance = ________

6. With power applied to instrument system, perform the following voltage tests at the DPU locations:
a. J4 -10 BLK (meter com) to J4-11 RED (meter +)   (s/b = 5.00 VDC) . = ________

7. With engine running:
(a.) J4 -10 BLK (meter com) to J4-12 WHT (meter +)   (s/b = 2.2 to 2.7 VDC) . = ________
(b.) J4 -10 BLK (meter com) to J4-12 WHT (meter +)   (s/b = 2.5 to 3.3 VAC) . = ________

1.) Check that wires are correctly installed into DPU and have not broken or come loose. Inspect closely because a wire that has just broken may not be easy to detect. Give the wire a gentle pull to insure it is connected. Insure that wire is not touching adjacent wires or DPU case.
Repeat this inspection at the transducer end of the cable.

2.) Measure continuity of each wire from transducer terminals to appropriate DPU terminal block screw. There should be very low resistance if the wire is intact. If resistance is greater that 0.7 ohms, then stop and correct connections.  Resistances =  (WHT) ________, (GRN) ________, (RED) ________, (BLK) ________.

3.) With power applied to instrument system, perform the following DC voltage tests at the transducer:

(a.) BLK (meter com) to RED (meter +) = 5.00 VDC +/- 0.05 = _________________
(b.) BLK (meter com) to WHT (meter +) = 1.90 VDC +/- 0.20 = _________________
(c.) BLK (meter com) to GRN (meter +) = same as above = _________________
(d.) GRN (meter com) to WHT (meter +) = 0.00 VDC +/- 0.003 = _________________

With meter still connected as ‘d’ apply a known pressure to transducer. Calculate VDC for applied pressure using appropriate ratios as charted below.

OIL PRESSURE (100 psi max) = 0.0005 VDC / lb
INJC FUEL PRESSURE (50 psi max) = 0.001  VDC / lb.
CARB FUEL PRESSURE (15 psi max) = 0.0033 VDC / lb.

(100 psi max) = 0.0005 VDC / lb
INJC FUEL PRESSURE (50 psi max) = 0.001  VDC / lb.
CARB FUEL PRESSURE (15 psi max) = 0.0033 VDC / lb.

1. Check that wires are correctly installed into DPU and have not broken or come loose. Inspect closely because a wire that has just broken may not be easy to detect. Give the wire a gentle pull to insure it is connected. Insure that wire is not touching adjacent wires or DPU case.

2. Repeat this inspection at the transducer end of the cable.

3. Measure continuity of each wire from transducer terminals to appropriate DPU terminal block screw. There should be very low resistance if the wire is intact. If resistance is greater that 0.7 ohms, then stop and correct connections.
Resistances =  (WHT) ________, (GRN) ________, (RED) ________, (BLK) ________.

4.  Engine off,  instruments on.

5.  Measure at DPU with digital voltmeter. Readings should be steady.

(a.)  WHT J3-9 (Meter +)  BLK J3-12 (Meter com)  (s/b = 2.50VDC) = ________
(b.)  GRN J3-10 (Meter +) BLK J3-12 (Meter com) (s/b  = 2.45VDC) = ________
(c.)  RED J3-11 (Meter +) BLK J3-12 (Meter com)  (s/b =  5.00VDC) = ________
(d.)  WHT J3-9 (Meter +)  GRN J3-10 (Meter com) (s/b = 0.036VDC) = ________

Note: Steps a., b., c., may vary slightly if your altitude differs from sea-level.
Back View of (older style) transducer showing wire color connections for reference:

FUEL LEVEL PROBE TEST

1. Check that wires are correctly installed into EC100 or IO PCB and have not broken or come loose. Inspect closely because a wire that has just broken may not be easy to detect. Give the wire a gentle pull to insure it is connected. Insure that wire is not touching adjacent wires or case.

2. Repeat this inspection at the transducer end of the cable.

3. Using a high quality digital volt ohmmeter, measure continuity of each wire from transducer terminals to appropriate terminal block screw. There should be very low resistance if the wire is intact. If resistance is greater that 0.7 ohms, then stop and correct connections.
Resistances =  (WHT) ________, (RED) ________, (BLK) ________.
4. With power applied to instrument system, perform the following DC voltage tests at the transducer wires:
(a.) BLK (meter com) to RED (meter +)   (s/b = 5.00 VDC) .  = ________
(b.) BLK (meter com) to WHT (meter +)   (s/b > 1.9 VAC). = ________
(c.) BLK (meter com) to WHT (meter +)   (s/b 1.9 to 2.4 VDC). = ________

5. With probe disconnected from EC100 or IO PCB, measure resistance between probe wires as follows:
(a.) BLK (meter com) and WHT (meter +) wires. (s/b approx  14500 ohms) .  Resistance = ________
(b.) BLK (meter com) and RED (meter +) wires. (s/b approx  9100 ohms) .  Resistance = ________
(c.) WHT (meter com) and RED (meter +) wires. (s/b approx  5500 ohms) .  Resistance = ________

1. Check that wires are correctly installed into DPU and have not broken or come loose. Inspect closely because a wire that has just broken may not be easy to detect. Give the wire a gentle pull to insure it is connected. Insure that wire is not touching adjacent wires or DPU case.

2. Repeat this inspection at the transducer end of the cable.

3. Measure continuity of each wire from transducer terminals to appropriate DPU terminal block screw. There should be very low resistance if the wire is intact. If resistance is greater that 0.7 ohms, then stop and correct connections.
Resistances =  (WHT) ________, (RED) ________, (BLK) ________.

4. Measure resistance between the WHT and BLK wires. (s/b approx  = 5100 ohms) .  Resistance = ________

5. Measure resistance between the WHT and RED wires. (s/b approx = 4700 ohms).  Resistance = ________

6. With power applied to instrument system, perform the following DC voltage tests at the transducer:
(a.) BLK (meter com) to RED (meter +)   (s/b = 5.00 VDC).    = ________
(b.) BLK (meter com) to WHT (meter +)   (s/b > 0.30 VDC). = ________

Leaving meter connected as ‘b’ pump a steady uninterrupted stream of fuel flow through the transducer into a container. This should produce an AC voltage at the BLK and WHT wires of greater than 1.0 VAC.  = ________

To re-load engine hours, follow the steps below:

STEP 1 – ‘Accessing Set Mode’: With power off, press and hold buttons 1, 3, 5 and then turn on power. Wait until the displays start reading out values (takes about 15 seconds or less), and then release buttons.

STEP 2 – ‘Selecting decade to change’: Press button 4 once to move to the next higher decade on the digital engine hours display area. There is no visual indication of this, other than when you change the decade value (STEP 3). Pressing the button moves the selection to the left until it gets to the highest decade, after which the next press returns you to the lowest decade.

STEP 3 – ‘Changing the decade value’: Press button 5 to increase the decade value as desired. If you go over ‘9’ it will carry to the next decade. To erase the entire engine hour’s value, select the highest decade and increase it until the display clears. Do this TWICE, and then proceed per steps 1 thru 3.

STEP 4 – When you are satisfied with what you see, shut off the VM1000.

EGT / CHT probes are thermocouple devices and typically  The EPI800 and VM1000 systems check for an open probe when the system is first turned on. A probe that does not pass the checks is displayed as ‘Er’ in the corresponding cylinder switch position(s) on the EPI800 system and as a blank bargraph(s) on the VM1000 system.

If a probe becomes intermittent or fails inflight, the reading may appear as a random fluctuation in temperature which can climb very high or dip very low. If this occurs, you can re-cycle power and the system will attempt to recheck the probes. If the problem is constant, you have the best chance of identifying the errant probe(s), otherwise it may take some trial and error troubleshooting. The following steps will help you troubleshoot the suspected probe(s):

1. With the engine off, turn power ON to the engine instruments. After a short period of time, the system will be running.

2. Scan all CHT and EGT positions for ‘Er’ (EPI800) or blank graph (VM1000).  If all positions are ‘Er’ there is most likely  a DPU fault and the troubleshooting process can be stopped and the factory contacted. If not, the probe circuit(s) may be open. Perform the following test sequence for each suspected probe:

(a.) Shut off power.
(b.) With digital meter, measure resistance between suspect probe(s) leads, while still connected, at proper DPU terminals. Resistance should be less than 10 ohms.________
(c.) If yes, then record the resistance and contact the factory.__________
(d.) If not, then CHECK ALL CONNECTION POINTS for a clean secure connection. Because of the type of metals used in thermocouples, the leads can corrode and/or rust and must be scraped clean. Accomplish this and re-try from #1.

(e.) If the above step does not result in a solution, then the probe can be considered bad and no further troubleshooting is needed. Replace the probe.

(f.)  Measure for resistance to aircraft ground bus from each probe lead. This resistance check should be made on the 2 meg ohm scale of the meter. This value should be greater than 1 meg ohm. If not then the probe should be replaced.

DISPLAY BACKLIGHTING INOPERATIVE:

The backlighting power for the indicators originates in the DPU. A small invertor generates 0 to 80 volts AC depending on the amount of DC voltage applied to DPU J4 pin 16. Follow these steps to isolate the cause of the backlighting problem:

NOTE: All suceeding steps presume prior steps have passed.

If illumination is out on all indicators:

1. Verify dimmer power applied, DPU J4 pin 16 has the correct DC voltage (full brightness would be close to full battery voltage, measured with a voltmeter, from your dimmer system).

2. Listen to the DPU. A faint whine can be heard inside the DPU if the invertor is running. This test must be conducted in complete quiet and you must be within approximately 12 inches from DPU to hear it.

3. Shut off dimmer power and unplug the display cable from the DPU. Re apply dimmer power,  and listen again for the whining tone. If it is not present, then the problem is in the DPU.

4. Shut off dimmer power and unplug all indicators from the display cable, Reconnect display cable to the DPU.

5. With dimmer control applying full power to DPU J4 pin 16, CAREFULLY connect ONE indicator to display cable on the connector closest to DPU (this eliminates breaks that may be in cable further away). If the indicator lights up, then the first connector position AND indicator lighting circuitry are functional. Test the remaining indicators on this display connector.

If only some indicators are illuminated :

6. Shut off power. Remove the indicators that do not work.

7. Take a known working indicator and test each of the different connector positions on the display cable. Be sure to turn on full dimmer power after plugging into each postion. If certain positions test bad, then a new cable will have to be fabricated. If certain indicators test bad, contact us for assistance.

1. Check that wires are correctly installed into DPU and have not broken or come loose. Inspect closely because a wire that has just broken may not be easy to detect. Give the wire a gentle pull to insure it is connected. Insure that wire is not touching adjacent wires or DPU case.

2. Repeat this inspection at the pressure transducer end of the cable.

3. Measure continuity of each wire from transducer terminals to appropriate DPU terminal block screw. There should be very low resistance if the wire is intact. If resistance is greater that 0.7 ohms, then stop and correct connections.
Resistances =  (WHT) ________, (GRN) ________, (RED) ________, (BLK) ________.

4.  Engine off,  instruments on.

5.  Measure at DPU with digital voltmeter. Readings should be steady.

(a.)  RED J3-15 (Meter +) to BLK J3-16 (Meter com)   (s/b =  10.0 VDC) = ________
(b.)  GRN J3-13 (Meter +) BLK J3-16 (Meter com)   (s/b  = 10.0 VDC) = ________
(c.)  WHT J3-14 (Meter +)  BLK J3-16 (Meter com)  (s/b = 5.0 VDC) = ________

6. Leave meter connected as in step ‘5 c.’ A test can be done to see if amp sensor responds to current flow through it. Turn on a heavy load, such as the landing light and see below:

(a.) If your installation monitors ‘BATTERY CHG / DISCHG’ then the voltage between ‘WHT & BLK’ should decrease by approximately 0.036 volts per amp of current drawn from battery.  Note: Engine is OFF during this test.

(b.) If your installation monitors ‘ALTERNATOR OUTPUT LOAD’ then the voltage between ‘WHT & BLK’ should increase by approximately 0.036 volts per amp of alternator current drawn by the load.  Note: Engine must be running fast enough for alternator to produce current flow.

1. Check that wires are correctly installed into DPU and have not broken or come loose. Inspect closely because a wire that has just broken may not be easy to detect. Give the wire a gentle pull to insure it is connected. Insure that wire is not touching adjacent wires or DPU case.

2. Repeat this inspection at the transducer end of the cable.

3. Measure continuity of each wire from transducer terminals to appropriate DPU terminal block screw. There should be very low resistance if the wire is intact. If resistance is greater that 0.7 ohms, then stop and correct connections.
Resistances = (RED) ________, (BLK) ________.

4.  Engine OFF,  instruments ON, with approximate temperature at 70 deg F.

5.  Measure at DPU with digital voltmeter on best range for measurement. Readings should be steady.

OIL TEMP TESTS
(a.)  J4-1 (Meter +),  J4-7 (Meter com) (s/b = 4.70 VDC) = ________
(b.)  J4-2 (Meter +),  J4-7 (Meter com)  (s/b  = 98.9 mVDC) = ________
NOTE: A Oil Temp indicator reading of 26 means the probe is not delivering a signal to the DPU. The most common cause is an open connection, or a short in the cable causing the signal to be grounded.

OAT TEMP TESTS
(a.)  J4-3 (Meter +),  J4-7 (Meter com) (s/b = 4.70 VDC) = ________
(b.)  J4-4 (Meter +),  J4-7 (Meter com)  (s/b  = 98.9 mVDC) = ________
NOTE: An OAT indicator reading of -50 means the probe is not delivering a signal to the DPU. The most common cause is an open connection, or a short in the cable causing the signal to be grounded.

CAT TEMP TESTS
(a.)  J4-5 (Meter +),  J4-7 (Meter com) (s/b = 4.70 VDC) = ________
(b.)  J4-6 (Meter +),  J4-7 (Meter com)  (s/b  = 98.9 mVDC) = ________
NOTE: A CAT indicator reading of -50 means the probe is not delivering a signal to the DPU. The most common cause is an open connection, or a short in the cable causing the signal to be grounded.

Note: Readings will vary slightly for temperature different from 70 deg F.