February 24, 2013 at 3:54 am #1830
NO check engine light on I got in the van started down the road, went to accelerate would not go over 2000 rpm, running fine yesterday a tech said something about cam sensor, or transmission selector switch, ecu not letting engine rev due to fail-safe mode any ideas??February 25, 2013 at 2:53 pm #6311
Fail-Safe mode is activated by the Transmission Control Module (TCM) when a major electrical device has failed or when the vehicle has been driven under extreme conditions.
To confirm Fail-Safe mode, turn ignition key to ON (do not start), O/D amber light blinks for about 8 seconds.
Can you described previous operating conditions? If the speed sensor was starting to fail before going into fail-safe (erratic speed indication in speedomoter), then replace the speed sensor. If speed sensor was OK, Was the RPM indicator erratic before going into fail-safe? If yes, replace revolution sensor. If not, we need more information.
Did someone worked in the auto transmission before?
The troubleshooting procedures are extensive and hard to type all in here without having more details.
PedroFebruary 25, 2013 at 5:58 pm #6312
Thanks Pedro, just purchased van last week, don’t no any history 103.000 miles, nice clean van, everything worked fine until SAT. morning, changed fuel filter, no change in condition, no check engine light, checked for pending codes anyway w scanner, nothing, only have a autoxray 6000 scanner, the only thing that looked out of place was the coolant temp reading 371F, at operating temp on dash guage, unplugged went to -40 ? will try to confirm O/D amber light, this morning would not start, cranked over , but no start. used carb spray in throttle, will start and idle till spray gone. will check connector at trans todayFebruary 25, 2013 at 11:15 pm #6314
The O/D light on dash comes on steady then goes out, must not be Fail-safe mode on trans, cooling fan on radiator runs w key on or run position,Was the RPM indicator erratic before going into fail-safe? If yes, replace revolution sensor? rpm on tach drops once it goes over 2000 rpm on the engine in park or driving, CPS in Dist? ecu? wiring?February 26, 2013 at 4:25 pm #6315
The ECM can also go into fail-safe mode. In this mode, the engine does not go over 2400 RPM. However, when ECM goes into this mode, the SERVICE ENGINE light will go on and you should be able to read a DTC code. If you don’t get any permanent or pending codes, then it is something else or the ECM module itself. I would not consider ECM failure as first option.
You said you replace the fuel filter and you say it is not starting now. Based on that info, I would start checking the fuel pump. Make sure you have fuel flow or better check the fuel pressure, it should be around 43 psi. If you confirm fuel, then check for spark. If you have an inductive timing light, you can use it to check for spark. You don’t have to remove the plug.
Let’s start with that.
PedroMarch 13, 2013 at 6:08 am #6358
UPDATE::: The 371F degree reading on Coolant temp sensor was the problem, DID NOT set code, replaced sensor temp reads 189 to 215 on scanner runs greatMarch 14, 2013 at 2:11 pm #6362
Great to know you got it fixed. You have also provided valuable information about the temp sensor and the effects it can cause without having a code in the ECU. Diagnosing a propblem without a code is really difficult.
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