Cars & Trucks - Recent Questions, Troubleshooting & Support
BMW 1990 535i Wont start No Spark
may need a noid or led 12volts test light.
check power at ignition coil, check signal at the ignition coil, check signal at fuel injectors.
It may be a security system, no crankshaft sensor signal, bad ignition coil, ignition rotor
1990 BMW 5...
1 hour ago
2004 Trailblazer 4.2L no crank.
85 & 86 are the control side of the relay , one should have battery voltage (85) the other (86) doesn't .86 is control from the PCM - engine computer . PCM supplys a ground to close contacts inside the relay sending battery voltage to the S terminal on the starter solenoid . If the PCM doesn't see a voltage signal fron the park neutral safety switch it won't energize the relay .
Circuit Description (ECM/PCM Controlled)
Moving the ignition switch to the START position sends a 12-volt signal to the engine control module (ECM)/powertrain control module (PCM) Crank Request circuit. The ECM/PCM verifies that the transmission is in the PARK or NEUTRAL position. With the transmission in Park, voltage flows through the Park/Neutral position switch and feeds the starter relay coil. The PCM then grounds the control circuit of the starter relay. When the starter relay is energized it allows battery positive voltage to the starter solenoid S terminal. On some vehicles the starter will continue to crank the engine with the key released until it starts or the crank command has timed out to prevent excessive heat build up in the starter circuitry or the ECM/PCM receives an engine run flag.
Cars & Trucks
1 hour ago
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