Loss of VOLTAGE- Relays energize then click off


#1

I have a SERIOUS problem with a '92 Dodge B250 van, 5.2 SFI.- Every time I turn the Ignition key to the “Run” position, I loose all voltage going to the, "ASD (Auto shut-down) relay, and the Relay that feeds all the Sensors and injectors. Engine cranks but will not fire -up Because the Relays Click and then click again cutting off the voltage going out…Resulting in no spark comming out of the coil. The Crank position sensor is new, as is the pick up coil and the coil itself. Plugs, wires, cap and rotor new also. PLEEEEEEASE HELP.


#2

A quick look at a schematic shows that the ASD relay should have power provided at all times from an in-line fusible link through a red wire.

The ASD relay should have a dark blue wire that is powered up when the key is in both the START and RUN position.

If it’s the former then the link is burnt. If the latter either the electrical part of the ignition switch is bad, there is a wire connector problem between the ASD and the switch, or there is a bad resistor in the circuit, even though the schematic does not show it.


#3

Maybe I misunderstood your post. With the key on, the ASD relay will only energize for a second or so, unless the engine is cranking or running.

Are there any codes?

With the engine cranking, the dark green wire with the orange strip at the coil and injectors should be hot, if it isn’t, then that leads back to the ASD relay or control circuits. It is possible to use a jumper on the proper two terminals at the ASD relay, that will supply voltage to everything the relay controls, I’d probably use a fused jumper. Even with voltage, if the proper signals from the rotational sensors are missing, it still won’t start.

This is probably a long shot, but, I have heard of the 02 heater circuit causing problems, you might unplug that circuit, see if it makes any difference?


#4

Maybe, you missed my last post to your question at cars.com. Were you ever able to bring up the wiring diagrams at www.autozone.com? Alternatively, you can go to your public library and ask a librarian to help you get the wiring diagrams from www.alldata.com, or another web site. +++ The PCM (aka the computer) LETS the ASD relay energize by providing a ground for the dark blue/ yellow wire. IF the proper signals do come into the pcm from the crank postion sensor and the cam position sensor, the relay will continue to be energized. If no signal, no energizing, or, no maintained energizing. The Haynes, or Chilton’s usually instruct on how to check the crank and cam positon sensors. Does yours?


#5

According to the schematic, power is provided at all times through the red wire and through the dark blue wire when the key is in the RUN and START positions.

The relay may energize for a second or two but that is because the relay has been provided an electronic ground through the ECM. The power supply is supposed to be a constant, unless the fusible link, ign. switch, or possible resistor block is at fault.


#6

me_art12: I did miss your last post, but did however print out and referr to your verbal instructions many times…it was a very big help. I have peeled ALL of the factory tape on the wires and have traced the wires numerous times. seems as if I AM getting constant voltage to the Relays in question, but nothing out. I am getting voltage to the PCM but nothing OUT via the Black/Blue wires that feed the sensors and the injectors. I did retrieve a schematic from the Mitchels software mechanics program…but dosen’t answer the main problem or probable cause. If I can get that DAMN ASD relay to hold voltage I might be OK. Any suggestions are appreciated…Thanks!


#7

Since you state you ARE getting voltage to the ASD (through both the red and the dark blue wire I assume), and if the relay is not kicking this means a problem in the ECM the way I read it or a lack of a pulse from the electronic ignition to the ECM.

If you’re getting power at both of those wires then the next thing I would do is connect a test light to the POS side of the battery and probe the dark blue/yellow wire at the ASD.
The test light should illuminate when the key is on and the engine is being cranked over. This would mean that an internal ground is being provided for the ASD relay.
If there is a ground, then it would seem to me that the relay itself may be bad; possibly burned contact points.

I would also think that if one used the test light as a probe between the dark blue/yellow ASD wire and ground you should hear the relay click, activate, and the vehicle should start. If it works this way, then the problem should go back to the ECM again.

Hope that helps.


#8

ok4450: That’s a VERY good suggestion…, Hooking up the test light to the POSITIVE side of the battery and testing the output signal FROM the ASD (via the dark Blue/yellow wire). I will go back to the shop and perform the tests you have stated. Although I have a sneaky suspicion that the PCM is bad ( this is the SECOND one), being I have no voltage or signal comming out of the PCM via the Black/blue wire that feeds the signal to the coil and the pick-up coil in the dist. Also: The Oil pressure sensor is bad, and I have been jumping the the imputs with a jumper wire to fool the PCM into thinking there is oil pressure, but the only way I can get the guage to move is to short it to ground (the Imput terminals). You’ve been a big help…I’ll let you know how the tests go. Thanks!


#9

ok4450:- I ran over to the shop and ran your suggested tests. You Wrote Saying the “Dark blue/Yellow” wire at the ASD…Threre is no Dark blue/Yellow wire at the ASD…I’m assuming you got confused and Meant the dark GREEN /yellow wire (Which there is), Taking that into consideration, I hooked the test light to the POSITIVE side of the battery, turned the ignition to the on position and I DID get a light at the Green/yellow wire at the ASD. AS for the second test,-Green/yellow wire to ground with the test light did NOT energize the ASD with or without the ignition on. Those Relays should energize and stay energized…(When turning the key to the ON position), why they don’t is beyond me…after all… they are brand new and act the same way as the old set.(I’ve swapped them a couple times) Also, The Crank Position sensor is brand new, and the vehicle does NOT have a Cam sensor.( unless you consider the pick-up coil in the dist. to be the cam sensor)( Which is also new). Now what’s the next move?..LOL!


#10

You’re right about the wire color. Dark green it is; I was still thinking blue from the ignition switch.

I’ll take a closer look at the schematic on this and post back later.
Just to verify again. The red lead at the ASD is hot all the time and the blue is also hot in both RUN and START positions?

I’m not a huge Chrysler expert but it seems to me the ASD should ground through that dark green wire but it may be only for a few seconds when the key is turned on.
When the engine is cranked over the ground will reappear is my best theory.

Back later on this. Be patient; we’ll get there. (hopefully)


#11

After going back and looking at the schematic, I guess I was right the first time.
The red should be hot all the time.
The dark blue should be hot in RUN and START.
The dark blue/yellow should be ground through the ECM.
The dark green/yellow is the power output lead of the ASD relay (coil, injectors, etc.)and should be powered up IF the dark blue/yellow wire is grounded, either with a test light or through the ECM.

I sure find it odd that (according to the schematic) that this vehicle does not use a fuel pump relay and runs the fuel pump current through the ASD relay also.

The way I look at it, at this point, is that if the red wire is hot, the dark blue is hot, and the dark blue/yellow is grounded, then the relay should energize and power everything up through the dark green/yellow.
With the key in the RUN position and grounding that dark blue/yellow everything should be working and even the fuel pump should be heard humming along.


#12

In the heading of your question, you have “…5.2 SFI”. Doesn’t SFI mean (Single point Fuel Injection)? Otherwise know as “throttle body fuel injection” (TBI)? And is your van a Sportsman? A few pages back, I think I asked you if it is MFI (Multipoint Fuel Injection) or throttle body? My response was based on MFI. The difference is: the power wire FROM the ASD is dark green/orange. IF it’s TBI, the power wire from the ASD is dark green/black. Now, DOES it have a throttle body or eight (8) fuel injectors? [I forgot to login. I’m me_art12].


#13

OK4450, The Fuel Pump circuit is shown in a separate diagram. If you do a parts look-up at www.partsamerica.com [Advance Auto Parts], you’ll see that the ASD relay and the Fuel Pump relay are Siamese twins (joined by a bracket]. Often on the side of the relay is printed its internal diagram. One can use that to check across the pins for the relay’s pull-in coil (pins 85 & 86 ?), unenergized continuity between pins B+ on pin 30 and out pin 87a, energized B+ pin 30 and out pin 87. These numbers are usually next to each pin (terminal). ++++ The relay(s) are NOT the problem. They are energized for a few seconds. The PCM is un-energizing the relay(s). Why? Lack of signal getting through from the Crankshaft position sensor, or the camshaft position sensor (in the distributor)? The signal from each would be a pulsing dc voltage under 5 volts (I think). A digital voltmeter MUST be used. If not, the PCM, or any electronic module, will be fried. With the engine not running, the circuits and sensors can be checked for resistance (ohms) and continuity (no broken, or high resistance, wires, or loose connections).


#14

Like I said, use a jumper and bypass the ASD relay, see if the vehicle starts and runs. If it does, the problem is in the relay or control circuits. If it doesn’t the problem is elsewhere. I would double-check the signals from the rotational sensors. I’m not saying the sensors are bad, just make sure the computer does see the signal. Any codes?

Where I come from, SFI means," sequential fuel injection".


#15

I just wanted to add, if you try the jumper use a fuse.


#16

Thanks Shadetree. You’re right. SFI does mean Sequential Fuel Injection (which is MFI). SFI means that each fuel injector sprays in the sequence of the cylinder firing order. +++ Tonka, As several people have said, it seems there is a missing sensor signal to the computer (PCM)…either, the cam position signal (CMP sensor), or, the crank position signal (CkP sensor). +++ I found that WIRING DIAGRAMS CAN be downloaded and printed from www.autozone.com. Do a right click on the upper left corner of the image. +++ A common power source comes from the PCM (black/light blue wire), and goes to: ALL the engine sensors. Signal from the cam position sensor is via a tan/yellow wire to terminal 44 on the PCM. Signal from the crank position sensor is via a gray/black wire to terminal 24 on the PCM. With the engine cranking, digital volt meter set on 20V dc, positive probe touching a terminal (wire STILL in place), you should see a varying indication on the meter. +++ As I said before, www.autozone.com is the place you wanna be. Go there. Input your vehicle data (1992 Dodge B250 5.2L MFI). For the sensors, you can get the Operation, and Testing, and Removal & Installation instructions. Click under Chrysler Full Size Vans 1989-1998 Repair Guides. Click on Driveability & Emissions Controls > Electronic Engine Controls > select a sensor, or etc. +++ You might consider a shop, if you continue to have problems.


#17

Bump


#18

Have you tried reading the codes? Toggle the ignition switch on and off three times (but not in the starter position) on the third time leave it in the on position the check engine light should come on as a bulb check then the following blinks will be codes. Four blinks followed by a pause, then two blinks, then a longer pause then five blinks a short pause then five more, and then light stays out. This would be code 42 auto shutdown circuit fault, and code 55 end of fault codes, if you have recently disconnected the battery then you will also get a code 12 and or code 13 as well. let us know if you can pull the codes and post them back


#19

This board is going screwy. This was post #69. I couldn’t flip back to it until I clicked on Topic Index; then, chose Car Questions; then, scrolled to the bottom of each page and clicked NEXT.


#20

UPDATE: Sorry for the couple a days lapse guys, I don’t want to seem dis-respectful. Well, after all of our hard work, Leg work, homework, and determination to get that DAMN van to fire up…The Customer came Monday wanting his van back fixed or not, so I re-Taped all the wiring back up, Re-assembled the engine components, and towed it back to his house Tuesday morning. I must say gentlemen that in 34 years of being in business this is the FIRST time I had a Vehicle that left my shop un-fixed. Although I don’t get many Dodge vehicles come my way…certainly NOT with a Cluster (BLEEP) of wires hanging out of the bottom of the dash, and an alarm system that refused to cooperate untill I yanked it out.
Anyhow, I DO want to SINCERELY thank the Following Mechanics: me_art12, ok-4450, and shadetree- For ALL of their Time, Knowledge, and willingness to help me with this Monstorous Electrical problem…YOU GUYS are all 5 star mechanics in MY BOOK!..If we lived in the same State, I’d sit us down at the nearest bar and Hoist a few beers and stories!
Thanks once again for all your individual time and patience…may we meet again on better circumstances.
Take care gentlemen.

Tonka