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Bypassing Asd Relay


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14 replies to this topic

#1 BobKat

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Posted June 13, 2006 at 01:35 pm

I suspect that there is a bad Crank Position Sensor or other sensor in my '96 Sebring Convertible. I think that a sensor's intermittent cutout is what is causing my car to die very suddenly when going over bumps or potholes in the road. The car ALWAYS starts again perfectly after 10 or so seconds.

I want to try to bypass the ASD relay in order to test this. I think that when the sensor cuts out it is killing voltage across the relay and shutting down fuel and spark.
Am I correct that if I get a proper spare relay, remove pin 87A, and jump pin 86 to pin 87, that this will effectively bypass the relay when the key is on, and always supply power to my fuel pump, injectors, and such? Am I also correct that this relay is not cut off except in conditions like a bad sensor reading? In other words, in ordinary driving, the ASD relay is not used to meter or control delivery of voltage for spark and fuel, is that correct? It's only a cutoff when abnormal conditions are detected? I want to take a short drive with the relay bypassed to see if my car keeps stalling over bumps. I have spare relays from a parts car and can remove pin 87 and solder a tiny jumper between 86 and 87. I do NOT want to burn anything up. :-/

86 supplies voltage when the key is on, 30 supplies it all the time. Should I use 30? I would think not.

#2 AllanC

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Posted June 13, 2006 at 02:04 pm

A better solution would be to take the car to an Autozone parts store and get the powertrain control module (PCM) scanned for any diagnostic codes. This should be a free service. The crankshaft position sensor (CPS) does not control the ASD relay directly. The CPS provides information on crank position / piston position along with information from the cam position sensor. The PCM interprets this and determines the optimum time to pulse the fuel injector and fire the spark plug for any particular cylinder. If this CPS signal is lost, the PCM shuts down the ASD relay and the fuel pump. This is a safety related feature to prevent the electric fuel pump from running after a collision and a resultant fuel line rupture.

It appears that you have a loose connection. A diagnostic scan should indicate which sensor is having a signal problem. Maybe all you need to do is remove, clean and reinstall a connector. Also it is possible that you have a wire shorting intermittently against the engine or body or any other metal piece in the engine compartment. Check wiring harnesses in and around the engine compartment.

You should NOT jump terminal pin 86 to pin 87 at the ASD relay socket. Pin 86 gets its power from 1 of multiple circuits through the ignition switch. You very certainly could place an electrical overload on the ignition switch if you connect these 2 pins together. This ignition circuit would then be directly powering and carrying the electrical load for the fuel pump, fuel injectors, ignition coil, and other things. This ignition circuit was NOT designed to carry this much electrical load.

#3 BobKat

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Posted June 13, 2006 at 02:10 pm

Recently, I was getting a P0171, which has now gone out as I believe that code was caused by a tank of bad gas. It immediately went out after putting some fresh gas in and the car is running perfectly now with the exception of the aforementioned stalling. No CEL light at all now.

If I key danced, would it throw a code through the CEL, if the CPS was bad?

If in fact I do decide to try to bypass the relay, failing any codes appearing, would pin 30, which is 12V all the time and I assume comes direct from battery voltage, be a better source of 12V power?

I belive that in normal operation, when the ASD is energized, that the relay connects pin 30 to pin 87, and when it is de-energized, it connects it to pin 87A, which essentially leads nowhere. Is that correct? And, if so, then the relay being "manually" energized by connecting 30 to 87 would, in effect, bypass the relay. I would just have to be sure not to let the car sit for any legth of time at all with the relay jumped and the car not running.

Edited by BobKat, June 13, 2006 at 02:14 pm.


#4 AllanC

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Posted June 13, 2006 at 02:23 pm

OBD II diagnostics started with 1996 and later models. That is a letter (such as P) followed by a 4 digit code which is only readable with a scan tool. But many on these forums indicate that the key dance sequence still will get the check engine light to flash a 2 digit code so it certain is worth the effort to see if you can get a code in that manner.

I belive that in normal operation, when the ASD is energized, that the relay connects pin 30 to pin 87, and when it is de-energized, it connects it to pin 87A, which essentially leads nowhere. Is that correct? And, if so, then the relay being "manually" energized by connecting 30 to 87 would, in effect, bypass the relay.


You have an accurate grasp of the functioning of the ASD relay.

#5 BobKat

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Posted June 13, 2006 at 02:50 pm

Thanks. 1996 is a hybrid year; you can get codes from the key dance as well as from the OBDII scan tool; I will do a key dance and will also get a reading from a scan tool; I do know that sometimes codes do not show up when in fact thye should, so I will consider the relay idea as well. It is by NO means a permanent fix in my mind, or even a short-term fix to drive the car; it is merely a diagnostic "port in a storm" and I do NOT intend to jerry-rig the car, it's not my style.

#6 BobKat

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Posted June 13, 2006 at 03:41 pm

Key dance reveals codes

12- (no biggie- I know this is the recent battery disconnect code)

14- MAP Sensor voltage

42- ASD Relay Interrupt OR Fuel pump relay Interrupt (I think I need OBD-II to tell me more).

55- end of codes.

Now, I disconnected the MAP sensor the other night while the engine was running. Could that have thrown these codes? Wouldn't the code have reset itself when I started the car with the MAP sensor reconnected? Or does this possibly indicate a bad MAP sensor?

#7 John Wood

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Posted June 13, 2006 at 04:51 pm

Now, I disconnected the MAP sensor the other night while the engine was running. Could that have thrown these codes? Wouldn't the code have reset itself when I started the car with the MAP sensor reconnected?


Yes, disconnecting the MAP sensor would be the cause of the stored code 14. It will eventually clear itself out, but it might be a month or so before that happens (50-60 engine re-starts with no repeat of the code). Disconnecting the battery will clear it, but may result in the transmission having to go through a re-learn process. If your MAP sensor is OK, the computer will use its information. The stored code is just for reference in case the problem comes and goes (it gives the tech something to go by).

#8 BobKat

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Posted June 13, 2006 at 08:28 pm

Add a code 11 to the mix, which I think clinches the crank position sensor as the cause. On a '96, I think the engine will continue to run with the cam position sensor inactive.

#9 AllanC

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Posted June 13, 2006 at 09:50 pm

42- ASD Relay Interrupt OR Fuel pump relay Interrupt (I think I need OBD-II to tell me more).


Yes, the OBD-II codes probably would give more information. The relay control circuit can set a diagnostic code. The relay slave circuit also can set a diagnostic code. I would suggest you check the wiring going into the ASD relay socket. Go to this link at Autozone and repair guides.

http://www.autozone....23d801edc62.jsp

Scroll until you find your vehicle and engine. Note that the ASD relay has 4 wires going into its socket in the power distribution center. You need to check each of these wires at the socket and make sure the connections are tight and not shorted to ground. It is also possible that the contact points inside the ASD relay are burned, pitted and corroded. It is possible to take 2 small flat blade screwdrivers and pry and remove the cover from the ASD relay. A little piece of fine sandpaper pushed across the contact points will clean them quickly.

On a '96, I think the engine will continue to run with the cam position sensor inactive.


No. The cam position sensor signal is necessary along with the crankshaft position sensor to determine timing for fuel injector pulse and spark plug firing.

Edited by AllanC, June 13, 2006 at 09:53 pm.


#10 KOG

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Posted June 14, 2006 at 03:47 am

It's possible to bypass any relay by using a short jumper wire with two male connectors. You don't need another relay to do this. You do need to be very careful not to plug your jumper into the "hot" side of socket and then let the other end of the jumper touch a ground. I've used this trick on A/C clutch and fan relays as well as ASD when a relay problem was suspected. And I've not driven the car with a jumper installed, just let it run at idle while checking for trouble.

#11 BobKat

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Posted June 14, 2006 at 08:29 am

My first check is going to be to get underneath and have a look at the crank position sensor. I was under the car recently and maybe I knocked a connection loose. I'll clean the connections on the crank sensor, take it for a ride, and see what happens (as the stalling over firm bumps is very easily reproducable). Then I will in turn check the cam sensor.

The PDC is very clean and connections are good.



In addition, I am going to scan the OBDII codes and get a read on that.

#12 KOG

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Posted June 14, 2006 at 08:50 am

You should be able to reach the crank sensor connector from the top by removing the air duct to the throttle body.

#13 BobKat

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Posted June 14, 2006 at 06:04 pm

Holy Cow. Really? That explains some behaviors I noticed when checking the harness. Thanks.

I'll have a look and let you know what transpires. You guys have been a world of help.

#14 BobKat

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Posted June 17, 2006 at 10:56 am

I took the day off yesterday to have a good look at all of this nonsense.

I put the car on ramps and looked at the CPS. I discovered that the valve cover gasket was leaking oil down th eback of the block and into the connector for the CPS. Oil filled the connector and wreaked havoc. New valve cover gasket.

I also discovered that the harness for the CPS and oil pressure switch had been damaged in the past and fixed rather hurriedly. I undid the substandard work, soldered and shrink-tubed the wires, added a new piece of wire loom, and taped and routed the repaired harness out of any harm's way.

The car is running very well and not cutting out anymore at all.

Thanks for all of the insights and suggestions. They were a big help in understanding the functions of the system, which was instrumental in the final diagnosis.

Bob

BTW, on the 2.4, the CPS is practically at the bottom of the engine, right rear. On ramps it is easy to get to but from the top, not possible. Maybe the v6 is what you are thinking of.

#15 KOG

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Posted June 17, 2006 at 12:03 pm

Yes, I was thinking of 6.


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