Coolant Flow Diagnostic Code - Proheat M80 Service Manual

COOLANT FLOW: Step 1
WARNING
NEVER remove coolant lines when
the engine is hot – escaping steam
or scalding water could cause
serious personal injury. Loosen the
coolant line clamps slowly,
allowing the pressure to escape
before removing completely.
COOLANT FLOW: Step 2
PROHEAT M-SERIES SERVICE MANUAL
3.1.3

COOLANT FLOW Diagnostic Code

(3 flashes) Indicates that the coolant temperature in the PROHEAT reached 185°F (85°C)
within 90 seconds from the beginning of Ignition. There is coolant in the
system but its flow rate is too low.
Troubleshoot the Coolant Flow diagnostic code based on:
1. Vehicle coolant system. Go to Step 1.
• The PROHEAT starts and runs for 90 seconds or less and shuts down
with a Coolant Flow diagnostic code indicated.
2. Coolant Pump system electrical or mechanical fault. Go to Step 2.
• The PROHEAT starts and runs for 90 seconds or less and shuts down
with a Coolant Flow diagnostic code indicated.
Vehicle coolant system – Check:
a) For restrictions and blockages in the coolant lines.
(3 Flashes)
b) OEM system shut-off valves for correct operation.
c) For loose hose clamps – air introduced into the system.
d) Coolant line size, fittings. Are they too restrictive?
e) Direction of flow. Are the PROHEAT Coolant Pump and the engine Coolant
Pump pumping in the same direction when they are operating at the
same time?
f) Coolant capacity. Is there enough coolant in the system?
Specifications, page 1-1.
g) PROHEAT location. Is the PROHEAT or Coolant Pump the high point in the
system? Coolant Pumps are not self-priming and a surge tank may
be required.
Coolant Pump and PCM – Check:
(3 Flashes) a) PCM electrical function.
b) Coolant Pump electrical function.
c) Coolant Pump mechanical function.
Test Procedure – Electrical:
a) Disconnect the Coolant Pump connector at the PCM.
b) Using a multimeter set for voltage, switch the PROHEAT on and measure
across pins A and B on the PCM Coolant Pump connection.
If the correct nominal system voltage (12 or 24) is measured, the PCM is
OK. Go to Procedure – Mechanical inspection and testing, page 3-26.
If no voltage is measured, the PCM is faulty.
page 3-39.
Go to Technical
Go to PCM replacement,
3-25