Don't Let The Click fool You
Posted to Technical Tips Forum on 3/22/2017
14 Replies
Today, a 2017 Malibu was towed in with a no crank failure.
The customer told us that his mechanic said that the starter
had failed as a click can be heard from the starter when the
start button is pressed but the starter does not activate.
It was towed to the dealer as it is still under warranty.
There were no codes set in any module. Looking at ECM data
with key on engine off, i saw this...
[2017 Chevrolet Malibu LT, ECM/Inputs/Outputs Scan
Data]
Looks normal. Now, how about when the starter button is
pressed?
[2017 Chevrolet Malibu LT, ECM/Inputs/Outputs Scan
Data]
OK,The ECM is receiving a start request and is activating
the crank relay. I heard a click coming from the starter
area. This is a stop/start vehicle and, as such, it uses two
starter relays. One relay is used to engage the starter
drive into the flywheel and the other is used to actually
crank the starter. The starter solenoid has two control
wires leading to it, one from each relay.
Why two relays? With the stop/start system, when the vehicle
autostops, the pinion relay is activated, engaging the drive
into the flywheel with the engine off. On the autostart, the
other relay is activated, causing the starter to crank the
vehicle. Why? because is shortens the crank time, making the
autostart less noticeable. During a push button start, both
relays are activated sequentially as a normal starter.
I pulled both relays and checked power inputs - OK. I jumped
both relay connections and one caused the drive to extend
and contract and made the click noise heard. Jumping the
other relay connection caused the starter to free spin. This
is normal operation. I hooked a test lamp to battery
positive and probed the ground side of the starter relay and
it illuminated with the start button pressed, showing that
the ECM was activating the relay, but the relay was not
functioning. A new relay solved the problem. No starter
needed.
James from Florida
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