Cummins ISB CM550 (1990-94) Fault Code: 434 PID: SID 251 SPN: 627 FMI: 2 Unswitched Battery Supply Circuit
Circuit Description
The ECM receives constant voltage from the batteries through the unswitched battery wires
that are connected directly to the positive (+) battery post. There are three in-line 7.5-amp
fuses and one 20-amp fuse in the unswitched battery wires to protect the engine harness from
overheating. The ECM receives switched battery input through the vehicle keyswitch wire,
when the vehicle keyswitch is turned on.
Component Location
The ECM is connected to the battery by the engine harness. This direct link provides a
constant power supply for the ECM. The location of the battery will vary with the equipment
manufacturer. See the equipment manufacturer repair manual.
Shop Talk
NOTE: If a battery disconnect switch is turned off after the keyswitch is turned off, but before
the ECM completely powers down (up to 20 seconds) this fault may register.
Make sure that ECM unswitched power is coming from the batteries and not the starter or other device. Check for low voltage during cranking. Low voltage during cranking can cause the ECM power supply to drop below specifications and log Fault Code 434.
Corrupted voltage (short interruptions or spikes that may only be seen with an oscilloscope) on
keyswitch line can cause this fault. If the voltage at pin 5 of engine connector is measured as
negative with oscilloscope at key-off, Fault Code 434 can be logged.
Related
-
PF Diagnose 2.0.2.23 Diagnostics Software 2013 – Full Heavy & Medium Duty with OBDII Support – Online Installation Service
PF Diagnose $60.00Rated 0 out of 5 -
International Truck ISIS – Oncommand Service Information Q4.2020 [04.2020]
Navistar $85.00Rated 0 out of 5
-
CAT CDVR PC Software – Caterpillar Digital Voltage Regulator (CDVR) WINDOWS 10
CAT $45.00Rated 0 out of 5 -
Volvo Intermediate Storage File Encryptor/Decryptor (Editor) VISFED 0.3.2
Trucks software $35.00Rated 0 out of 5 -
Bobcat Service Library [03.2019] Service, Operator, Maintenance, Bulletines, etc full update
Bobcat $110.00Rated 0 out of 5 -
JPRO 2022 v1 Commercial Vehicle Diagnostics V1 Software Download & Installation Service ( 1 PC )
JPRO $94.00Rated 0 out of 5 -
PF Diagnose 2.0.2.23 Diagnostics Software 2013 – Full Heavy & Medium Duty with OBDII Support – Online Installation Service
PF Diagnose $60.00Rated 0 out of 5 -
DAF Davie Runtime v5.6.1 Davie XDc ll [02.2019] + Expire Fix 302.00 Unlock ( Windows 7 )
DAF $70.00Rated 0 out of 5
Related products
-
Allison 1000 & 2000 Gen 4 Fault Codes: P0846 Transmission Pressure Switch Solenoid D Circuit Stuck Open
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U1016 Class 2 J1850 (Class 2) Powertrain Controller State of Health Failure
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P1891 Engine Throttle Position Sensor Pulse Width Modulation (PWM) Signal Low Input
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0875 Transmission Reverse Pressure Switch Circuit Malfunction
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U2105 CAN Bus ECM Error
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U2104 CAN Bus Reset Counter Overrun
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0848 Transmission Pressure Switch Solenoid D Circuit High
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0870 Transmission Pressure Switch Solenoid E Circuit
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U0073 CAN Bus Reset Counter Overrun
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P2771 Four-Wheel Drive Switch Circuit
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P2773 Torque Control Request Ignored – ECM/TCM
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0872 Transmission Pressure Switch Solenoid E Circuit Stuck Closed
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U1064 J1850 (Class 2) TBC Controller State of Health Failure
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U0032 J1850 (Class 2) Serial Data Communication Link High
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0122 Pedal Position Sensor Circuit Low Voltage
1000 & 2000 Gen 4 $50.00Rated 0 out of 5
-
SERVICE MANUAL International Engines DT466E & DT530E (1999 & Older)
INTERNATIONAL ENGINES $31.00Rated 0 out of 5 -
SERVICE MANUAL International Engines MaxxForce DT 9 10 (2010-2013)
INTERNATIONAL ENGINES $20.00Rated 0 out of 5 -
SERVICE MANUAL International Engines MaxxForce DT 9 10 (2007-2009)
INTERNATIONAL ENGINES $30.00Rated 0 out of 5