Hello all, I recently rebuilt my engine and dropped it in the cruiser. Been hooking everything up and attempting to get life back in this thing. I've been doing quite a bit of testing and checking yet the ECM seems to not want to be in a ready state. I am mostly wondering if anyone knows the types of conditions that would cause the ecm to not be ready. It seems that because of this no power is being sent to my circuit opening relay. The ECM will respond when I bridge B+ and W on my diag port, I see the CEL on solid and then I get 3v at the B+ and the VAF terminals. Otherwise these terminals get 0V. I think I might have ruled out the VAF b/c the problem doesn't change when I unplug the VAF like I've seen in other threads. I bridged my fusible links to try and eliminate that, still the same. I keep looking through the fuses and relays and they all seem fine each time. As of now my knock sensors aren't plugged in because the terminals got busted on each of them. Would not having single pin knock sensors hooked up throw the ECM in a shutdown state? Are there any types of collision sensors or something that will cause the ECM to shutdown?
'94 cruiser not getting CEL on startup. (1 Viewer)
- Thread starter bhagga424
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Malleus
Far west of Siegen
My first guess is you're missing a ground. There are several on the engine alone.
Your post doesn't describe how you know "bridging" the FLs proves they're good. Electrical troubleshooting requires, at least, a multimeter; simply bypassing a component and observing a similar fault before and after the fact doesn't prove that component is not faulty. I'd recommend checking the voltage from the battery to engine bay fuse block, before you try to use the FSM ECU troubleshooting matrix.
There are no "shutdown states" in which the engine would not start, which are programmed into the ECU. There's a limp mode, but that doesn't prevent the engine from strarting or running. The neutral safety switch will prevent starting, if the circuit cannot establish a "park" or "neutral" position.
Your post doesn't describe how you know "bridging" the FLs proves they're good. Electrical troubleshooting requires, at least, a multimeter; simply bypassing a component and observing a similar fault before and after the fact doesn't prove that component is not faulty. I'd recommend checking the voltage from the battery to engine bay fuse block, before you try to use the FSM ECU troubleshooting matrix.
There are no "shutdown states" in which the engine would not start, which are programmed into the ECU. There's a limp mode, but that doesn't prevent the engine from strarting or running. The neutral safety switch will prevent starting, if the circuit cannot establish a "park" or "neutral" position.
- Thread starter
- #3
thanks for your response. I've been tracking down the grounds and I can no longer find any missing. Two of the legs on my fusible link had cracked insulation and corrosion. I replaced those legs with some regular wire for the time being while the new link comes. I have been using a multimeter to continuity test and check voltages all over. Spent some more time checking around and its looking like the always on terminal of the ECM is interrupted. I'm checking at the E1 pin on the diag port. I get miniscule voltage like in the mV at that terminal. I put my multimeter in diode test mode to get the beeps for continuity. Between the (+) term on the battery and the efi fuse I get a beep. Between the EFI fuse and the and the E1 pin, no beep but a resistance is being picked up. I do get a beep between the E1 terminal and ground, guessing this is my sign I,ve got a short there and power can't get to the ECM?
Malleus
Far west of Siegen
The Diagnostic Test Connector (DTC) isn't the right place to validate the ECU connections. It'll work for a side of the road analysis, buy you need to use the ECU troubleshooting matrix in the FSM to determine where to look for faults. The complete FSM is in the Resources section. You can download it for free.
Unfortunately, wihtout knowing the complete, or at least the recent history, you need to start at step one and fix whatever you find at fault. Here are the three section you need to get started:
Unfortunately, wihtout knowing the complete, or at least the recent history, you need to start at step one and fix whatever you find at fault. Here are the three section you need to get started:
Malleus
Far west of Siegen
Here are the system operation description, current flowchart and the engine ground points:
The check engine light often comes on because of transitory problems. If the error causing the light stops for some reason, the light will turn off and the computer will enter into a "learning" mode but still show an error. Take your car to an auto parts store and they'll read the error codes on your car's computer for free. Pop that code into Google with your make and model and you'll find out what it is and how to fix it.
Couple of things jump out here.
The E1 pin on the diagnostic port is GROUND.
The "always on" pin of the ECU is E7 pin 2. That is fed directly from the 15 amp EFI MAIN fuse which is fed from fusible link MAIN (blue). It is not available on any diagnostic connector.
Without having the proper documentation you're just pissing into the wind. Everything you need is available to download in the resources section.
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- Thread starter
- #8
Awesome thank you for these great documents. At the ecu I'm not getting any voltage at the BATT terminal. Fuse is good. Tried to run a continuity test between this terminal and the fuse and i keep getting an open circuit. The ground pins check out so far.
Once again, all information is available for you to download free fer nothin' in the resources section.
If you look at the engine control section, you'll find a schematic of the complete ECU and associated circuits. You'll then notice that the wire that feeds B+ to the ECU passes through connector EA2 pin 2.
Again, referencing the EWD, connector EA2 is just below the fender mounted relay box.
Download the EWD and FSM.
Here, let me hold your hand:
