Lingenfelter L460260704 Lingenfelter CAN to Analog Gauge & Relay Output Module CAN2 v1.0 - Manual (Page 22)

CAN2-002 Install & Operating Instructions 22
© 2014 Lingenfelter Performance Engineering
CAN2-002 m odule being connected to GMPP crate engine harness in one of the
LPE engine dynam om eter cells.
2.6.3 Terminating resistor
High speed CAN networks operate on twisted pair wires with termination resistors at each end of the
network.
In custom vehicle applications that involve engine swaps into vehicles that did not originally have CAN it
may be necessary to add a terminating resistor to the CAN network. The CAN2-002 module does not
provide any internal termination. This is done to allow the device to be installed almost anywhere in an
existing CAN network.
High speed GMLAN and most other CAN configurations use two 120 Ohm termination resistors placed
between the GMLAN+ and the GMLAN- circuits. One termination resistor is usually located inside the
engine control module (ECM)*. The other is sometimes located inside another module but it is most
often a stand-alone resistor taped into the harness. The network can operated with one open resistor
(with one missing resistor) but the signal will be less stable and communication errors may occur.
To test the CAN network for the existance of the termination resistors, connect an Ohmeter (or DVOM
set to resistance measurement) across terminals 6 and 14 of the DLC with the key OFF.
The resistance should read 60 Ohms if both resistors are ok (since the resistors are in parallel).
If the resistance reads 120 Ohms you have one open resistor (one missing resistor).
If the resistance reads infinity (open connection) you may have 2 open resistors but it is much more
likely that you have a poor connection at the DLC.
If the resistance reads 0 Ohms (or close to it) the GMLAN +/- circuits are shorted together.
*On some engine control modules (ECM) and other vehicle modules, two sets of CAN terminals may
exist on the module with one set of terminals configured with internal termination for use when the
module is going to be at the one end of the circuit and another set of terminals that do not have internal
termination for use when the module is not going to be at the end of the circuit and then some other