Engine/Transmission (1994 - 1998) can the crank shaft sensor be bypassed?

[JRosengrant]

Icant Get A New Sensor Until Tuesday, But I Need My Truck For The Weekend. Is There Anyway To Get The Charging System To Work Without The Sensor?

 

[HoleshotHolset]

Sure - full field the alternator with a toggle switch.



Matt

 

[therabbittree]

the alternator should work separate of the crank sensor. . i thought the crank sensor was for the factory tach on the second gens?

Thanks,

Deo

 

[HoleshotHolset]

The crank sensor provides the ECM with the engine RPM. That value in turn looks up a table (based on voltage and battery temperature) and determines the proper rate of charge...



Matt

 

[therabbittree]

sounds strange i have never seen a alternator like that... im used to vw and older alternators. . i was under the understanding if you have a mechanical pump engine the ecm was just there for the abs brakes basically... i know my '89 and '92 run fine with out any ecm... . The alternator should just have a voltage regulator that limits the max volts output. . and the amps it the potential load it can handle and maintain the charge.....

if the dodge has some funky snesor to tell the alternator it needs so and so volts etc that sound very strange to me compared to most alternators i've taken apart and fixed... I guess i learn some thing every day . . if that is the case i will swapping alternators if i was you . . ha

later

deo

 

[Howard Durand]

Do a search on voltage regulators, I have seen a couple of posts here where the PCM voltage regulator had failed and a standard voltage regulator had been used to replace it.

 

[JRosengrant]

If I Full Field The Alternator, What Wires Do I Use So That I Dont Send To Much Into The Pcm

 

[vssman]

Deo,



One of the "wonderful upgrades" Dodge did when they designed the 2nd gen was to eliminate the voltage regualtor that was used in the 1st gen trucks and instead have the PCM control alternator output. They also have the PCM control the AC cycle too. I guess it was too reliable and too many of us knew how to fix the systems if they didn't work... :-laf



Paul

 

[K5IP]

If you are sure the crank sensor (engine speed sensor) is bad, fine, but be aware that many suspected bad sensors are actually caused by a bad sensor connector located just above the sensor itself. Opening it up and spraying come contact cleaner on it usually fixes it. It (the connector), seems to be a common failure. I have to wire it together with a nylon tye wrap on my 95 to keep it working. Also, check the sensor to damper gap. Use a non magnetic feeler gauge (brass). Gap should be . 049 to . 051 in. Sometimes they were never set right in the first place and as things age, they become more particular. Some folks use a plastic credit card, but mine only measure . 030".

By the way, according to my manual, the sensor provides the information to the pcm which signals closure of the Auto shutdown relay. This (ASD) provides the positive 12 VDC battery voltage to one side of the field. The other side of the field is returned to ground through the electronics of the PCM. If you full field the thing, be sure you remove the connector between the alternator and the pcm or you can damage the pcm if you screw up.

Rog

 

[PToombs]

Rabbittree, your '92 has a ECM, look in the fender behind the battery. My '92 needs the crank sensor to run the alternator. I think the '89 has one also!

 

[therabbittree]

The '92 has the pcm behind the battery in the fender well but, the '89 does not... I know for sure, as my '89 fenders are off now... and I moved my battery tray and stuff when I mounted the second gen intercooler etc. . maybe I'll be swapping the '89 alternator in too. . as both don't have the abs valve any more and the '92 is getting a fuel shut off cable. . and a gutted fuel shut off solinoid. . so I want full manual no ecms

Thanks

Deo

 

[Howard Durand]

Just out of curiosity, what happens if you use a steel feeler gauge to check the gap on the engine speed sensor?

 

[K5IP]

Howard,

I don't know, but the Dodge manual is quite specific that it be non magnetic.

The sensor is a hall effect switch, guess I need to do some research to satisfy my own curiosity.

Rog

 

[tp0d]

Just out of curiosity, what happens if you use a steel feeler gauge to check the gap on the engine speed sensor?

Nothing really... The sensor is magnetic, and a steel gauge will stick to it, and you possibly might get a bad depth reading... The whole sensor itself is coated in plastic. .



Then again, you could cause damage to the sensor by holding a piece of steel on it for any amount of time. I know most hall effect sensors fail due to lost magnetism, as there are no moving parts internally.



-j

 

[K5IP]

tpOd

I agree, you are right on all counts. And, if as you say hall effect sensors fail mostly due to lost magnetism, perhaps the guys who are setting the clearance with a plastic credit card (narrower gap) have hit on something that makes up for the lower magnetic field.

Rog