Exhaust Temperature Scanner Caterpillar

Wiring

Usage:

Wiring for the 285-6670 Pyrometer

Wiring for the Power Supply

The range for the input voltage is 10 to 32 VDC. A 12 volt supply or a 24 volt supply can be used.

Show/hide table




Illustration 1	g01228884
Wiring for the power supply (1) 160-7689 Connector Plug As (2) 186-3736 Connector Socket (3) 5P-5623 Electrical Wire (4) 109-3038 Wire End

Refer to Illustration 1. Be sure to observe the correct polarity as electrical wire (3) is installed. Crimp wire end (4) to the end of each wire. Connect each wire end to the appropriate terminal on the terminal strip inside the panel. Crimp connector socket (2) to the end of each wire. Insert each wire into the correct location on connector (1) .

Wiring for the Thermocouples

Channels that are Connected to Thermocouples

Note: All of the wiring for the thermocouples must be type K.

The pyrometer has a channel for each thermocouple. For example, channel 1 represents the number 1 cylinder. The wiring from each thermocouple is connected to the terminals for the corresponding channel. Channels 21 through 24 are used for the thermocouples for turbochargers.

The cable for the thermocouples has a pair of wires inside the insulation: one of the wires is yellow and one of the wires is red. The yellow wire is the positive wire for a thermocouple. the red wire is the negative wire for the thermocouple. The polarity of the wires must be maintained or the readings will be incorrect. Table 1 lists the connections for thermocouples for various engines.

Show/hide table

Table 1
Identification of Terminals on the 285-6670 Pyrometer
Channel No.	Terminal No.	Description	G3606 3606	G3608 3608 3508 G3508	G3612 3612 3512 G3512	G3616 3616 3516 G3516
1	1	Positive wire for thermocouple 1	Cyl 1	Cyl 1	Cyl 1	Cyl 1
1	2	Negative wire for thermocouple 1	Cyl 1	Cyl 1	Cyl 1	Cyl 1
2	3	Positive wire for thermocouple 2	Cyl 2	Cyl 2	Cyl 2	Cyl 2
2	4	Negative wire for thermocouple 2	Cyl 2	Cyl 2	Cyl 2	Cyl 2
3	14	Positive wire for thermocouple 3	Cyl 3	Cyl 3	Cyl 3	Cyl 3
3	15	Negative wire for thermocouple 3	Cyl 3	Cyl 3	Cyl 3	Cyl 3
4	16	Positive wire for thermocouple 4	Cyl 4	Cyl 4	Cyl 4	Cyl 4
4	17	Negative wire for thermocouple 4	Cyl 4	Cyl 4	Cyl 4	Cyl 4
5	24	Positive wire for thermocouple 5	Cyl 5	Cyl 5	Cyl 5	Cyl 5
5	25	Negative wire for thermocouple 5	Cyl 5	Cyl 5	Cyl 5	Cyl 5
6	26	Positive wire for thermocouple 6	Cyl 6	Cyl 6	Cyl 6	Cyl 6
6	27	Negative wire for thermocouple 6	Cyl 6	Cyl 6	Cyl 6	Cyl 6
7	32	Positive wire for thermocouple 7	Shorted	Cyl 7	Cyl 7	Cyl 7
7	33	Negative wire for thermocouple 7	Shorted	Cyl 7	Cyl 7	Cyl 7
8	34	Positive wire for thermocouple 8	Shorted	Cyl 8	Cyl 8	Cyl 8
8	35	Negative wire for thermocouple 8	Shorted	Cyl 8	Cyl 8	Cyl 8
9	40	Positive wire for thermocouple 9	Shorted	Shorted	Cyl 9	Cyl 9
9	41	Negative wire for thermocouple 9	Shorted	Shorted	Cyl 9	Cyl 9
10	42	Positive wire for thermocouple 10	Shorted	Shorted	Cyl 10	Cyl 10
10	43	Negative wire for thermocouple 10	Shorted	Shorted	Cyl 10	Cyl 10
11	48	Positive wire for thermocouple 11	Shorted	Shorted	Cyl 11	Cyl 11
11	49	Negative wire for thermocouple 11	Shorted	Shorted	Cyl 11	Cyl 11
12	50	Positive wire for thermocouple 12	Shorted	Shorted	Cyl 12	Cyl 12
12	51	Negative wire for thermocouple 12	Shorted	Shorted	Cyl 12	Cyl 12
13	10	Positive wire for thermocouple 13	Shorted	Shorted	Shorted	Cyl 13
13	11	Negative wire for thermocouple 13	Shorted	Shorted	Shorted	Cyl 13
14	12	Positive wire for thermocouple 14	Shorted	Shorted	Shorted	Cyl 14
14	13	Negative wire for thermocouple 14	Shorted	Shorted	Shorted	Cyl 14
15	20	Positive wire for thermocouple 15	Shorted	Shorted	Shorted	Cyl 15
15	21	Negative wire for thermocouple 15	Shorted	Shorted	Shorted	Cyl 15
16	22	Positive wire for thermocouple 16	Shorted	Shorted	Shorted	Cyl 16
16	23	Negative wire for thermocouple 16	Shorted	Shorted	Shorted	Cyl 16
17	28	Positive wire for thermocouple 17	Shorted	Shorted	Shorted	Shorted
17	29	Negative wire for thermocouple 17	Shorted	Shorted	Shorted	Shorted
18	30	Positive wire for thermocouple 18	Shorted	Shorted	Shorted	Shorted
18	31	Negative wire for thermocouple 18	Shorted	Shorted	Shorted	Shorted
19	36	Positive wire for thermocouple 19	Shorted	Shorted	Shorted	Shorted
19	37	Negative wire for thermocouple 19	Shorted	Shorted	Shorted	Shorted
20	38	Positive wire for thermocouple 20	Shorted	Shorted	Shorted	Shorted
20	39	Negative wire for thermocouple 20	Shorted	Shorted	Shorted	Shorted
21	44	Positive wire for thermocouple 21	Shorted	Shorted	Left Turbocharger Inlet	Left Turbocharger Inlet
21	45	Negative wire for thermocouple 21	Shorted	Shorted	Left Turbocharger Inlet	Left Turbocharger Inlet
22	46	Positive wire for thermocouple 22	Shorted	Shorted	Left Turbocharger Outlet	Left Turbocharger Outlet
22	47	Negative wire for thermocouple 22	Shorted	Shorted	Left Turbocharger Outlet	Left Turbocharger Outlet
23	54	Positive wire for thermocouple 23	Right Turbocharger Inlet	Right Turbocharger Inlet	Right Turbocharger Inlet	Right Turbocharger Inlet
23	55	Negative wire for thermocouple 23	Right Turbocharger Inlet	Right Turbocharger Inlet	Right Turbocharger Inlet	Right Turbocharger Inlet
24	56	Positive wire for thermocouple 24	Right Turbocharger Outlet	Right Turbocharger Outlet	Right Turbocharger Outlet	Right Turbocharger Outlet
24	57	Negative wire for thermocouple 24	Right Turbocharger Outlet	Right Turbocharger Outlet	Right Turbocharger Outlet	Right Turbocharger Outlet

Crimp a socket (2) onto the end of each wire. Insert each socket into the appropriate location in connector (1) .

Take care not to damage the insulation during installation. Take precautions against later damage from vibration, abrasion, pinch points, and liquids in conduits. Additionally, it is essential to use the following practices:

Keep high voltage wiring at least 30 cm (12 inch) away from the thermocouples and the wiring for the thermocouples. Never wire thermocouples with any other wiring from sources of high power.
For diesel engines with electronic fuel injection, install the thermocouples at least 30 cm (12 inch) away from wiring for the injectors.
For spark ignited engines, never wire thermocouples through the same conduit as the ignition wiring. Use spark plugs with resistors for lower electromagnetic interference (EMI). Install the thermocouples at least 30 cm (12 inch) away from wiring for the ignition.

Show/hide table




Illustration 2	g01228922
Typical example of a retrofitting (5) 116-2652 Electrical Cable (6) 3S-2093 Cable Strap (7) 4P-8134 Clip (8) 5P-0537 Hard Washer

Cable (5) is tied into a bundle by straps (6). The straps are secured to the panel with clips (7). Washers (8) are used between the clips and the rubber mounts for the panel.

Normally, each thermocouple is wired directly to terminals at the pyrometer. This is the preferred method of wiring. For retrofitting of the pyrometer, cable (5) can be spliced to the wiring from the thermocouples.

Show/hide table




Illustration 3	g01228930
Typical example of splicing (9) 2H-2965 Wire Splice (10) 126-9424 Heat Shrink Tube (11) 5P-6009 Heat Shrink Tube

Crimp the ends of the wires into splices (9). Protect each splice with heat shrink tube (10). Additional protection is provided for each pair of splices by heat shrink tube (11) .

Avoid any additional junctions and/or splices in order to ensure that an accurate signal is transmitted to the pyrometer.

Unused Channels

The pyrometer is capable of monitoring 24 channels. The pyrometer is self-diagnostic. In order to avoid false diagnostics for the unused channels, the unused channels must be shorted. Do not wire the unused channels into the harness.

For example, a six cylinder engine with one turbocharger will typically use eight channels. Six of the channels are used for thermocouples at the cylinder exhaust ports. One of the channels is used for the exhaust inlet to the turbocharger. The eighth channel is used for the exhaust outlet from the turbocharger. The remaining channels are not used.

Show/hide table




Illustration 4	g01229012
Example of a jumper wire for an unused channel

Refer to Illustration 4. Crimp a socket (2) onto each end of a jumper wire. Install the jumper wire into the appropriate terminals for each channel that is not used.

Testing the Circuits for the Thermocouples

Disconnect the wiring for a thermocouple from the pyrometer before you test the wiring with an ohmmeter or other instrument. This will prevent possible damage to the pyrometer's sensitive circuitry.

Wiring for the Output Switches

The pyrometer contains two output switches. The output switches are solid state. Each output switch is rated for a maximum of 2 amperes at 35 VDC. Each output switch is normally open.

The output switches can be wired in order to activate alarms or shutdowns. For example, the number 1 output switch can be wired for an alarm and the number 2 output switch can be wired for a shutdown.

Refer to Table 2 for identification of the terminals for the output switches.

Show/hide table

Table 2
Terminals for the Output Switches
Terminal	Output Switch	Function
58	2	Return
59	2	Output
60	1	Output
61	1	Return

Refer to Illustration 5 for an example of the wiring for the output switches. In this example, the outputs are used to control relays.

Show/hide table




Illustration 5	g01230427
Example of the wiring for the output switches

Input for Engine Rotation

Terminal 62 is the input for engine rotation. Typically, this input is not used. When this input is not used, the circuit must be open. When the circuit is open, all of the setpoints are active. It is important for this circuit to be open during normal engine operation. Refer to Testing and Adjusting, "Start-up Sequence".

When this input is connected to ground, all of the setpoints and the output switches are deactivated. Therefore, the engine is not protected against problems with exhaust temperatures.

If this input is used, an open circuit indicates that the engine is running. An external contact must be provided in order to open the circuit when the engine is running. The external contact must ground the circuit when the engine is stopped.