Bad ASD Relay Symptoms
Usually starts by stalling while driving, progresses into not starting at all, often it will start after several attempts. Engine will have no spark, and you will not hear the fuel pump run when the key is turned on, therefore, no fuel pressure.
These same symptoms have been noticed if a Fuel Pump Relay goes bad or during a computer failure. The Fuel pump relay could cause a loss of spark.
What to check
First of all when you first turn the car on does the Check engine light for a couple seconds? It should as part of the self test when you turn the key on. If it does not then i may be a defective computer, or a burnt out bulb, if the bulb is burnt then you may have a code that you don't even know about. So check that out first.
If your car is a 95-97 perform the key dance. See link for instructions
If you have a 98+ you will need to go someplace such as Autozone, and have them do a free code check. A relay problem usually will not show a code, but if you get a code there is a good chance whatever the code is indicating is causeing your problem.
After the car has sat for a couple minutes with the key off, Turn the key to the ON position, but not far enough to engage the starter. Under normal conditions you will hear the fuel pump run for 2 seconds, to build pressure in the system. The fuel pump is located under the back seat and should be audible from inside the car, or get a friend to stand beside the rear of the car and listen for it.
Check for spark, pull one of the spark pug wire of a plug and insert the metal end of a screwdriver into the end of the wire. Lay the wire and screwdriver onto the metal part of the engine and have someone crank the engine. (dont touch the screwdriver while the engine is cranking or youll be screaming obscenities)
If you see spark and hear the fuel pump than your ASD and Fuel Pump Relays are both good. If you see spark and have no fuel pump noise then i could be the fuel pump relay (or the pump). If the car is experiencing intermittent periods of not starting, then you will need to try this several times. It is possible that the one time you perform these checks, could be the one time the car will start without trouble.
The ASD relay is mounted under the hood on the drivers side of the firewall. near the brake fluid master cylinder
Some cars will have 2, 3, or 4 relays in this position, depending on which transmission you have. The Fuel pump Relay is always on the left (passengers side) with the ASD relay beside it. Only Automatic trans cars have the EATX relay, and 95 models have a fourth relay of unknown function.
To replace the relays you have 2 options.
1. Go to the dealer and order a new one. I believe someone payed $20+ at the dealer.
2. Go to your local autoparts store or Radio Shack and buy a 30 amp Bosch style relay. This relay will plug right into your harness and is identical to the original expect it will not clip to the mounting bracket like the original. You can usually disassemble your original and new relays and reassemble the new relay “guts” into the original factory housing. This way it will mount to the bracket.
If this does not solve the problem you could be having computer problems, there are several outputs you can check on the computer, before pricing and looking for a new one, so if you are still having difficulties post again
this is actually a pretty easy circuit to deal with, and ill first explain to you how it works then tell you what you should look for...
a constant 12v is provided to the asd and fuel pump relay along with the pcm.
the pcm then has a KEY ON power circuit. when you turn the key on, the pcm now activates all KEY ON circuits (fuel pump is one of them). the pcm does this via a ground signal.
so the asd relay has 4 pins. 12v power constant, 12v power feed, ground, and 12v power KEY ON. the relay always has power via battery/fuse box, then gets power via another fuse when the key is turned on, then gets GROUND from PCM when key is turned on, then has a pin to deliver power to associated relay circuits.
once the relay receives a ground signal from the pcm, it triggers the relay and activates SEVERAL sources via a junction connector under the PCM. it sends power to the fuel pump relay, coil, alternator, crank position sensor, oxygen sensors and a few others.
the fuel pump relay in your case is next in line. it has a fused 12v constant source via battery/fuse box. 12v Key ON power via ASD relay (this is a power activated relay, where as the ads is ground activated), a aconstant ground, then a signal or power output pin (which goes to the fuel pump). At this point once the fuel pump relay gets its power signal from the asd relay it powers up the fuel pump for a time delay of only 3 seconds. the fuel pump gets its own ground fyi via another circuit. after 3 seconds you will not be able to check for power at any of teh ASD powered sources UNTIL you begin cranking or the motor is running.
now you know how the system works, grab a power source, and apply direct power to pumps power pin. if the pump primes and runs you have a good pump w no power source.
this time take fuel pump connector in hand, and a dvom, have someone turn the key on for u while you check for power at the connector to the pump. if you have power then the pump isnt ur issue... if you dont have power, move along to the fuel pump relay. check for power at the power pin from asd relay when you have a buddy turn the key on... remember you only have roughly 3 seconds to cheeck for power b4 the time delay which is set into the pcm turns off. and just keep following the circuit back until you find the problem/