Cummins ISX-CM870 Probelm

[mathura]

Cummins ISX Probelm
I am getting fault code 433 -intake manifold pressure sensor, replaced the sensor and same probelm.
I replaced barometic, exhaust pressure and oil pressure sensors but code 433 is still active.
Unplug manifold pressure sensor and the code changes to 123 as soon I plug sensor back the code 433 becomes active again.
I am now at a point that I do not know what else to do, I need some help.

Thanks

[mathura]

Need help here friends, many good cummins technicians are here on dk

Thanks

[jctech]

What are your pressure with Insite monitor readings, at keyon before starting.
Any other faults relating to sensors?

[mathura]

Pressure is zero for boost and there is no other fault codes active or inactive, however I disconnected manifold sensor while engine running and it showed 123 fault active and 433 inactive.

[spannermonkey]

I think you have a wiring harness fault, have you check the continuity of the harness? the fault 433 is for the sensor circuit not the sensor, but i dont have the TnR manual so i cant follow the troubleshooting tree. You need TnR manual to see what conditons that code is active, whether its a disconnection or a short to high/low... id say a short because the 123 code will be the disconnect code.

[jctech]

Pressure is zero for boost and there is no other fault codes active or inactive, however I disconnected manifold sensor while engine running and it showed 123 fault active and 433 inactive.

with engine stopped, what are the readings for oil pressure, exhaust pressure and boost pressure.

[Drolet8758]

Cummins ISX Probelm
I am getting fault code 433 -intake manifold pressure sensor, replaced the sensor and same probelm.
I replaced barometic, exhaust pressure and oil pressure sensors but code 433 is still active.
Unplug manifold pressure sensor and the code changes to 123 as soon I plug sensor back the code 433 becomes active again.
I am now at a point that I do not know what else to do, I need some help.

Thanks

Hi Mathura ,,

90 percent of this kind of problem is the exhaust gas pressure that are fail because , humidity, water, enter into the connector and with corroded terminal in socket in sensor the exh. gas pressure sensor reading is erractic, just unplug your sensor to see,,,,if there some green crapp stuff in connector = replace it,,,, also to 10 percent of the time you can have the oil pressure sensor that fail,,,,oil passing thru the sensor and goes in connector/terminal and cause some problem like that,,,,see that and let us no

[spannermonkey]

Follow Jctechs post in the cummins service manual thread and trouble shoot the fault code, looks like it maybe cause by low sensor circuit voltage to the sensor or tampering with the wiring harness, interest, insite says the ecm only monitors for this fault at 50rpm more than the set idle speed, is it active all the time?

[mathura]

Friends
I am going to work on it today and will carry out the checks for sensor readings and let you know.
I forgot to mentioned that there was no active fault code before, it only started after some work on the egr piping was done. The guy forgot to plug in the egr differential pressure sensor and it had 2 active codes, after I plug the sensor harness for the egr the fault for egr sensor became inactive and only the 433 code was active.

Thanks

[spannermonkey]

In the rouble shooting manual it specifically notes to turn off any exhaust fans in the shop when diagnosing this fault code as it can alter the reading of teh sensor. If this is applicable to your shop maybe try that as well

[mathura]

with engine stopped, what are the readings for oil pressure, exhaust pressure and boost pressure.

Hello jctech
Here are the pressures recorded

Engine stopped ignition on
oil press - 0 psi, boost press - 0 psi, barometic press 30 inhg, exhaust press -35 inhg.

AT IDLE
oil -38.8 psi, boost -0, barometic -30 inhg , exhaust37.5 inhg

AT 1500 RPM
oil -48, boost -23, barometic 30, exhaust 98

fault code 433 ACTIVE

Tested wiring to booost press sensor for continuity ok. However there is a 680 ohms resistance between pins 37 and 47, unplug exhaust gas pressure sensor and value changes to infinity.

Checked pins 1and 2 on exhaust gas sensor the reading is 680 ohms, checked for contunity with sensor unplugged ok.

Would appreciate some answers please

thanks

[Drolet8758]

Hello jctech
Here are the pressures recorded

Engine stopped ignition on
oil press - 0 psi, boost press - 0 psi, barometic press 30 inhg, exhaust press -35 inhg.

AT IDLE
oil -38.8 psi, boost -0, barometic -30 inhg , exhaust37.5 inhg

AT 1500 RPM
oil -48, boost -23, barometic 30, exhaust 98

fault code 433 ACTIVE

Tested wiring to booost press sensor for continuity ok. However there is a 680 ohms resistance between pins 37 and 47, unplug exhaust gas pressure sensor and value changes to infinity.

Checked pins 1and 2 on exhaust gas sensor the reading is 680 ohms, checked for contunity with sensor unplugged ok.

Would appreciate some answers please

thanks

replace exh. gas pressure and retry

[mathura]

replace exh. gas pressure and retry

I replaced exhaust gas pressure sensor with a known working sensor and probelm still exists.

However after removing harness from ecm and run some checks on the wiring the 433 code became inactive for about 10 minutes. I stop and started the engine a few times to be sure that the probelm is no longer there, after about 8 starts and stop four active codes suddenly appeared.

All 4 of the active codes are pointing to the same area.
435 -engine oil pressure circuit
433 -intake manifold pressure circuit
295 -barometic pressure sensor circuit
2554 -exhaust gas pressure circuit

If I unplug anyone of the four sensors while engine running, the above four faults becomes inactive and a new fault code is generated pertaining to the unplugged sensor, example if I unplug manifold sensor then code 123 is active only.

I am at a loss here simply not sure what else to do.

Your suggestion is well appreciated

[spannermonkey]

sounds like you have a 5v sensor fault. if all four of those faults become active, they use a common output from the ecm for all those sensors. but im still sure you are looking for a wiring fault.

[jctech]

I replaced exhaust gas pressure sensor with a known working sensor and probelm still exists.

However after removing harness from ecm and run some checks on the wiring the 433 code became inactive for about 10 minutes. I stop and started the engine a few times to be sure that the probelm is no longer there, after about 8 starts and stop four active codes suddenly appeared.

All 4 of the active codes are pointing to the same area.
435 -engine oil pressure circuit
433 -intake manifold pressure circuit
295 -barometic pressure sensor circuit
2554 -exhaust gas pressure circuit

If I unplug anyone of the four sensors while engine running, the above four faults becomes inactive and a new fault code is generated pertaining to the unplugged sensor, example if I unplug manifold sensor then code 123 is active only.

I am at a loss here simply not sure what else to do.

Your suggestion is well appreciated

That circuit has a 5V supply on pin 37 and return on pin 47
This is sensor circuit number 2, this circuit supplies the
Camshaft position sensor
Exhaust gas pressure sensor
Fuel pressure sensor
Boost pressure sensor
Real time clock battery
EGR valve position sensor
EGR differential pressure sensor

The other sensor circuit (number 1) has the engine oil pressure sensor and barometric pressure sensor on it.

Any of these sensors or the circuits could be the cause of the problem. The fault is occuring because at keyon, before starting the engine, the ECM checks the oil pressure, boost pressure, barometric pressure and exhaust pressure, all these should read 0 PSI or 30 in.hg. (14.7 PSI). You are getting the fault because your exhaust pressure is 37 in.hg. (18 PSI).

Monitor all the pressure sensors on that circuit, with the key on engine not running, and unplug the sensors 1 at a time and see what happens to the pressures on the other sensors.
You are looking for the one that returns your exhaust pressure back to 0. You need to be 100% certain that the exhaust sensor is good.
They all have a common supply and return, but if one fails, it can drag the sensor supply voltage low causing one or more sensors to give an out of range signal.