Archived 96, All Dash Instr. Stuck ON, No Tach, Low Volts

[LBrazdys]

96 dodge 4 x 4 2500, reg cab, all stock. w/309k. All original trans etc.



Turned the key and all the warning lights are stuck on. Voltmerter at 9 volts after key is on. I hear some relay making a loud noise upon turning key.

Truck runs fine but every damm idiot light stays locked on and there is no tach reading. Alternator is 14 months old.



I have a scan tool on the way... not till next week.



I have an OEM manual... ... ... ... ... . any ideas.





other stuff



2002 TDI Jetta

1990 ZX11 with NOS

 

[bmoeller]

Welcome to the TDR.



What you may be hearing, is the shutdown solenoid, or the big relay for the pull in circuit. The PCM controls the voltage for the alternator. I would check the magnetic pickup for the tach first. If no tach signal, low/no voltage from alt. Check the grounds also. Could be something is back feeding power somewhere. If that is the case, a bad ground can do weird things.

 

[LBrazdys]

Man... ... ... ... ... this stinks.



I put two new batteries in. Cleaned all the grounds and connectors I could get to.

I performed a test per 8C3 in the OEM book. Got about 1. 1 Volts with my little VM on the output trminal at "B", couldnt get any volatge testing the (-) circuitry. Check all the connections on thatg side.



Still have all of the idiot lights stuck on. Doesnt appear to be charging. Makes a loud clicking sounds (relay). Seems like something is staying on due to a call maybe from the ignition switch... ... ..... could this be the culprit?



I am am in doubt on that being the tach is dead also. I check the speed sensor at the connection only. It looked ok.



I dont have a scan tool yet and cant cycle the ket for the codes because the dam lights stay on anyway.



Any ideas?

 

[DavidC]

Cycling the key on a 96 will not tell you anything. It does not work like that until somewhere in the 2k's. Are your batteries actually at 9 Volts?. Relay for Grid heaters?. There was a post to disconnect the neg. side of the batteries, turn the key to the run position and then reconnect the batteries. This supposedly reboots the computers. Might be worth a try. I am not sure it would work with low batteries though.



Dave

 

[DavidC]

You can check this post for maybe some guidance or contact Marco. He may know something with your problem.

http://turbodieselregister.com/forums/showthread.php?t=123791&highlight=reboot



Dave

 

[LBrazdys]

I have an OEM 96 manual that has a key cycle produre in it. Is this procedure valid?



Man, man connections sure are clean on this truck. Still dont know what going on with this. Ill look at the suggested links.



Thanks guys.

 

[LBrazdys]

I tried the reboot procedure... ... ... ... ... ... . no dice.

Im tired... ... ... ... ...

 

[LBrazdys]

Batt' were at 12 to 12. 5 old vs new. System ain't chargin.

9 was . 9 or so on the resistance test for the (-) and (+) side test per OEM procedures.

Having no voltage on the ground side makes me think the Mopar 14 month old ALT. is toast. My original went 300K. Should have rebuilt that one.

 

[DavidC]

Could it be the battery Temp sensor telling it not to charge?



Dave

 

[LBrazdys]

Hmmm, would that yield a no tach function? I didnt check these connections yet. Ill try that tommorow. I am assuming a scan tool would pick up malfunctioning sensors.

I have VW TDI and I use Ross-tech VAG/COM. It has come in quite handy.

 

[DavidC]

No tach is usually a bad crank sensor. I am not sure where or what 96 uses. Could be a bad connection or sensor. An ohm check on the sensor should bring up something. Batt. temp sensor would just keep the alt. from charging or overcharge the batt. . 99 shows 9k to 11k across the temp sensor. I guess I would lay odds on the crank sensor or connection as you will not charge without the engine showing RPM.



Dave

 

[LBrazdys]

Ok... ... ... ... . do you have Ohm spec for the crank sensor. I cant check for an open real quick.



Thanks

 

[LBrazdys]

I mean that I "can". Its getting late.

 

[DavidC]

Ok... ... ... ... . do you have Ohm spec for the crank sensor. I cant check for an open real quick.



Thanks

Sorry, but no. Should be a one line in your manual but no specifics. I can only refer to a 99 which the diagram shows a potentiometer setup where 2 pins run thru a resistor (1 hot then resistor then ground,series circ. ). The wiper is the other pin.



Dave

 

[LBrazdys]

Checked the crankl sensor.



One VM measured 3. 9"M" ohm, pretty high, the other meter I has indicated an open.

I checked across K4 and K6, and not across the signal wire.



Looks like this could be the culprit heh?



Gonna check the batt sensor now.

 

[DavidC]

Sure sounds like it. Now we can go to bed. Let us know how you make out when you get it replaced. If it is anything like a 99 it will take approx. 3 good starts after you get it replaced to put out the lights. Unless you clear the codes with a scanner. Good Night.



Dave

 

[K5IP]

I agree with everyone pointing you toward the crank sensor (engine speed sensor)

This is the root cause of your problem.

Without an input from the engine speed sensor, the PCM will not enable the charging system.

Although the engine speed sensor can fail, the most common failure is the engine speed sensor connector located just above the sensor.

The sensor itself in a hall effect device having three leads going to it. One lead is an 8. 5Vdc reference. Another is ground, and the third is an output lead to the PCM which switches between 0 and 8 VDC each time a notch in the damper passes the sensor.

The switched voltage can be observed using a vom (volt-ohm-meter) while cranking the engine.

Again, if the engine speed sensor is not working (as verified by the tach) the system will not charge.

Rog

 

[LBrazdys]

Checked the Batt sensor and its reads 11k on both meters. Gonna clean up the connector and put it back together.



Since the tach function is out... ... ... . Im gonna go with speed sensor.



Any other ideas... ... ... I would hope it aint the ALT or PCM box.

 

[LBrazdys]

Thanks guys... . gonna get a sensor on order... ... I will let you know what happens.

 

[DavidC]

Be sure to go over that connection with a fine tooth comb that k5IP is referring to. You could have an open or high resistance there or the sensor is open as you read previously. I just do not want you to spend money and then find out it was a wire at a connection.



Dave