ELM327
Error Messages and Alerts (continued)
ERRxx
should go below the low limit, a ‘brownout reset’ circuit
is activated, and the IC stops all activity. In rare cases,
a sudden large change in VDD can also trigger a low
voltage reset.
There are a number of internal errors that might be
reported as ERR with a two digit code following. These
occur if an internally monitored parameter is found to
be out of limits, or if a module is not responding
correctly. If you witness one of these, contact Elm
Electronics for advice.
When the voltage returns to normal, the ELM327
performs a full reset, and then prints LV RESET. Note
that this type of reset is exactly the same as an AT Z
or MCLR reset (but it does not print ELM327 v2.0).
An LV RESET will also block automatic searches
through the CAN protocols, if bit 4 of PP 2A is a ‘1’ (it
is by default). This is done because most LV RESETs
seem to occur as a result of CAN wiring problems (the
transceiver is capable of passing very large currents).
Blocking of the CAN protocols is only done until the
next reset (AT Z, WS, etc.) or until an AT FE is sent.
One error that is not necessarily a result of an
internal problem is ERR94. This code represents a
‘fatal CAN error’, and may be seen if there are CAN
network issues (some non-CAN vehicles may use pins
6 and 14 of the connector for other functions, and this
may cause problems). If you see an ERR94, it means
that the CAN module was not able to reset itself, and
needed a complete IC reset to do so. You will need to
restore any settings that you had previously made, as
they will have been returned to their default values.
Beginning with v1.3a of this IC, an ERR94 will also
block further automatic searches through the CAN
protocols, if bit 5 of PP 2A is a ‘1’ (it is by default). This
is done because most ERR94s will be as a result of
serious CAN wiring problems. Blocking of the CAN
protocols remains in effect until the next power off and
on, or until an AT FE is sent.
NO DATA
The IC waited for the period of time that was set
by AT ST, and detected no response from the vehicle.
It may be that the vehicle had no data to offer for that
particular PID, that the mode requested was not
supported, that the vehicle was attending to higher
priority issues, or in the case of the CAN systems, the
filter may have been set so that the response was
ignored, even though one was sent. If you are certain
that there should have been a response, try increasing
the ST time (to be sure that you have allowed enough
time for the ECU to respond), or restoring the CAN
filter to its default setting.
FB ERROR
When an OBD output is energized, a check is
always made to ensure that the signal also appears at
the respective input. If there is a problem, and no
active input is detected, the IC turns the output off and
declares that there was a problem with the FeedBack
(FB) of the signal. If this is an initial trial with your
ELM327, this is almost certainly a wiring problem.
Check your wiring before proceeding.
<RX ERROR
An error was detected in the received CAN data.
This most often occurs if monitoring a CAN bus using
an incorrect baud rate setting, but it may occur if
monitoring and there are messages found that are not
being acknowledged, or that contain bit errors. The
entire message will be displayed as it was received (if
you have filters set, the received message may not
agree with the filter setting). Try a different protocol, or
a different baud rate.
LP ALERT or !LP ALERT
This appears as a warning that the ELM327 is
about to switch to the Low Power (standby) mode of
operation in 2 seconds time. This delay is provided to
allow an external controller enough time to prepare for
the change in state. No inputs or voltages on pins can
stop this action once initiated. !LP ALERT is printed if
PP 0F bit 1 is 1.
STOPPED
If any OBD operation is interrupted by a received
RS232 character, or by a low level on the RTS pin, the
ELM327 will print the word STOPPED. If you should
see this response, then something that you have done
LV RESET
The ELM327 continually monitors the 5V supply to
ensure that it is within acceptable limits. If the voltage
ELM327DSI
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