#84141, "ECU test - ASD relay output" Dec-31-04 07:27 AM by ShadowRuleZ
I found through the search a quickie on how to test the ECU. I went through and tested it, everything seemed to check out except for two things. I'm mainly concerned with the second one.
1) I have +5 to TPS and MAP. It is exactly 5, so I think the post that said it was supposed to be +9 was wrong.
2) The ASD relay output reads +12 when the key is "ON" and 0 when it is cranking. The post had said it should retain voltage while cranking. Can anyone confirm this? The fuel pump relay does keep +12 while cranking. I checked all four relays and they are all good as well.
2b) What does ASD stand for and what does it do? Edit: ASD seems to be an acronym for MFI which is the fuel injection. SO I guess I don't have a question on that any more.
#84144, "RE: ECU test - ASD relay output" In response to Reply # 0 Dec-31-04 07:25 AM by thedawg
What year is your car?
On the 95 ASD is the relay with the red/black wire, the red/white wire, the black/red wire and the black/white wire.
To test apply +12v to the black/white wire and -ground to the red/white wire. when this happens you should get continuity between the red/black wire and the black/red wire. When you remove the voltage from the coil you should lose continuity between the red/black and black/red wires.
ASD stands for Automatic Shut Down. It controls power to the fuel pump, ignition coil, fuel injectors, and portions of the power module. It's also called the MFI relay (Multiport Fuel Injection) for this reason. Basically, if your ECU loses one of its critical sensors, the ASD will kill the engine.
#84145, "RE: ECU test - ASD relay output" In response to Reply # 1
Yeah, I had tested the relays using that diagram yesterday. The relays are all fine.
This is the output from the ECU to the relay. It was the red w/white stripe coming from the ECU that read +12V while the key was in the "ON" position and 0 while cranking. Just trying to find out if that is correct or not.
#84147, "RE: ECU test - ASD relay output" In response to Reply # 2
The ASD relay should remain closed while cranking. in other words you should have 12+ while cranking at the output pin of the relay. since you have 0 that means you have no spark, no injector pulse!
#84149, "RE: ECU test - ASD relay output" In response to Reply # 3
Just to confirm that I understand this, I should have 12V at the relay. I have not checked the relay while it is plugged into the car. I have been checking the signal at the ECU, not the relay.
I do have spark on all four cylinders, a timing light was showing that although I have no idea if the timing was right.
#84203, "RE: ECU test - ASD relay output" In response to Reply # 4
the ECU sends out a neg signal to power the relay. check for 12+ switched at the relay not the ECU. If you timing light is reading spark during cranking then your ASD relay is switching as it is supposed to.
#84166, "RE: ECU test - ASD relay output" In response to Reply # 0
Originally posted by ShadowRuleZ It is exactly 5, so I think the post that said it was supposed to be +9 was wrong.
Cam angle and crank angle are +9v sensors. MAP, TPS are 5v.
______________________________ If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.
'95 Eclipse TurboGS (garage deco) '95 TSi AWD (restoring a survivor) '97 Talon ESi-T (poor impulse control) '99 Eclipse RS-T (daily beater) '13 Evo X (mostly stock) '17 Sienna (Middle Aged Dad Mobile)
#84238, "RE: ECU test - ASD relay output" In response to Reply # 5
From looking at my schematics, the red/white wire coming from the ECU to the ASD relay should show a ground, with the key on, and during crank. This is the ground to the relay's coil. At the same time, you sould see 12 volts positive on the red/black wire, also coming from the ECU. This powers the relay, and then sends 12 volts positve out the black/red wire to the coilpack and other engine sensors. If you are not seeing that ground on the red/white, or the positve on the red/black, then suspect a bad ECU. Just for the hell of it, get a new SPDT 12 volt relay(radio shack, or a remote start/alarm install shop), and plug it in to see what happens. I work with relays everyday at my job, and have seen bad ones where a test light or meter shows the relay outputing the voltage, but the internal contacts of the relay are too pitted and corroded to carry any useable current..hope this helps some
13.5 @108 MPH-2.2 60ft(stupid FWD!) S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential fuel injection) My webpage: http://eclipsed4evr.home.comcast.net -1998 Mitsubishi Eclipse RS-T- "Toy" -1992 Plymouth Laser Turbo AWD(SOLD) -2000 Honda CR-V(daily)
Search
Printer-friendly copy
1 User in Chat
