ECM trouble

Prior to replacing the ecm wiring need to be checked

use an ohm meter and check all wiring for open and short
check relays and fuses

Using an ohmmeter, check for continuity to ground on ECM terminals No. 10, 19, 39, 43, 50, 106, 112 and 118. See Fig. Below
Resistance should be zero ohms.
If resistance is not zero ohms, repair open to ground.
Using a DVOM, touch negative lead of voltmeter to a good ground. Using positive lead of voltmeter, backprobe each ground terminal at ECM connector.
With vehicle running, voltmeter should indicate less than one volt. If voltmeter reading is greater than one volt, check for open, corrosion or loose connection on ground lead.

Turn ignition switch to ON position.
Using a voltmeter, check for battery voltage between chassis ground and ECM terminals No. 38, 56 and 61.
If battery voltage is not present, check fusible link and fuse "G".
Turn ignition switch to OFF position.
Using a voltmeter, check for battery voltage between chassis ground and ECM power back-up terminal No. 70.
If battery voltage is not present, check for overheated relays, fusible links and wiring.