I'm having some issues with my relay wiring. I've studied the diagram and traced the wires and can't seem to figure this one out. The circuit has one wire from the ignition switch to the ASD and fuel pump relays and one wire from the ECM to the ASD and fuel pump relays. The wire from the ignition supplies power to switch the relay on when the key is on and the wire from the ECM also supplies power to the relay. So out of the four terminals used on each relay, three of them currently receive power and because of this, no power is supplied to my fuel pump. My question is, how important is the ASD relay? Can I cut the wire from the ECM and ground it out to make the relay work without detrimental effects? Seeing that one wire is from the ignition switch it would make sense that the wire from the ECM should be the ground. Does the ECM supply a positive current to the lead wire in order to shut the vehicle down but normally operate as the ground for the circuit? Any help would be great. Thanks.
had some trouble with my asd relay a couple weeks ago. im not sure if you can just ground the wire from the ecu but i would not suggest doing it. you say no power to the fuel pump? trying switching the relays around to make sure they are good and also check the ignition fuse inside the cab and under the hood.
The ASD relay is VERY important to the Jeep. When it powers up, it supplies power to the fuel pump and the ignition system (coil)
The PCM grounds one of the 4 wires when it sees a RPM signal from the Crank sensor.
Quick test: Swap relay with similar one, see if problem is fixed.
Another test: Key on, ASD relay removed. Check for power in each of the 4 pins of the relay socket. Use a test light or Meter set to volts. There should be power on 2 of the pins. The other 2 are PCM ground wire and supply to pump and ignition.
edit: To answer your last question in the original post: If you ground the wire yourself, the pump and ignition will power up, but, if the PCM doesn't see a signal from the Crank sensor, it will not pulse the coil or injectors. So, grounding the relay yourself will not fix the problem.
I start what I finish!
Last edited by Curly5759; 03-17-2010 at 11:00 PM..
Reason: more info
What year jeep is it? i just got done working on a fuel problem and found there was a blown maxi fuse. check the engine control fuse. there should also be another relay in the relay box labled fuel pump. grab a tester and see if your getting 12 volts key on engine off at either terminal 87 or 30 <it should be labled on the relay> if you just want to test your fuel pump get a jumper wire and jump 87 and 30 without the relay installed. the pump Should come on if you have 12 volts.
The engine and wiring are from a '94, its a brand new sending unit/pump that I tested already. All the fuses and relays have been out and checked prior to this. I have power at the fuse box and the applicable relays as that is something I checked prior to attempting to start the engine for the first time. I should add that I'm doing a 4.0L swap on a YJ but since the wiring came from a cherokee I thought it would be best to post my question here. I guess I'll check my crank sensor next since that seems to be where the original data comes from.
Here is a good one folks....I was replacing my left front door quad switch when I inspected my kick panel fuse box. What I had found was a vacant #11 fuse for the Transmission control module, powertrain control module, automatic shutdown relay, fuel pump relay. There is no 20 amp fuse in place - at all!
My application is a 1997 XJ Jeep Cherokee with a 4.0 High Output engine. Everything seems to be running okay. I have no major issues with the performance except at speeds of 65 mph plus with some, either tire or drive-train, vibration.
DO I PUT A 20 AMP FUSE BACK INTO THE VACANT #11 FUSE HOLDER? I bought the vehicle used and have no idea what the original owner was thinking. I am afraid the close the circuit because I may open up a can of worms.
If anyone can shed some light on my situation - PLEASE RESPOND!
Thank you so much for your time!
Yes I am sure it is number 11. Number 10 is dedicated to Transmission range sensor, duty cycle evap/purge solenoid, radiator fan relay, a/c clutch relay, o2 sensor up/downstream relays, back up lamp switch. My AC is awesome and relay fan kicks on when needed - so not number 10. as I said, number 11 is vacant.....maybe it is because my 4x4 transmission is an Aisin AX-4 which is also used in some of the Toyota 4Runners..???
I am still confused. I have not put a fuse back in the vacant number 11 fuse holder as of yet. I need to know the details before I do so. If there is anyone else out there that has sincere knowledge of fuse number 11 and knows why my vehicle is not affected without it, please respond. Thank you!