99gs30067

Hopefully someone on her can help me with a issue I’m having. I have a 99 gs 300 that had a bad battery so I replaced battery and vehicle will start only for a few seconds and turn off. I hook scanner up to it and it will communicate for around 1 minute and then lose communication. If you try to start the vehicle once it loses communication it just turns over. If you remove the key and put it back in is has communication for around another minute and will run for a few seconds. Another weird thing is if your able to command the fuel pump on within that 1 min the car will stay running with no throttle response.

I sent the car to Toyota and they said it needed a new ecm so I purchased one and they reprogrammed the key but still the same issue.

Arsenii

Hello,

What happened to the old battery? Was there any parasitic draw?
Does the car have any alarm or security system, or any aftermarket mods?

Sounds like you are losing main power somewhere after that minute. Check that the voltage is at least 12V when the car is off, and that you have charge when the car is running. Then check the voltage at all main points during that minute of the scanner connecting, like B+ terminal on the OBD2 connector, Injectors and Coils, AM2, IGN and EFI fuses, etc., if it disappears on everything after a minute, you will likely have to dig into the fuse box to see if there is something out of place.

If that won't help, hook up to 5V bus on any sensor and see if it would get lost, if so, it is the wiring or the ECU. Next, check what is getting lost when the car dies - use an LED test light to probe injectors and coils to see what stops working, which may yield some useful information. If it is the main power, check the fuses again, if it is the Ground that is lost, check the ECU and its connections.

Hope this helps and best of luck!

99gs30067

The battery had a dead cell. I have 12.8v with car off and around 14v when running. One thing that’s odd is when you command pump on or bypass fuel ecu the car runs and sounds fine but get gets hot cause fans will not come on.

also the AC will not come on unless commanded to, the engine coolant gauge never moves even when engine is hot, outside temp shows 2 dashes and gear selection light on dash will not light up. Obviously this is all related, but just don’t know what would make all of these act up at the same time.

99gs30067

After one min the black/yellow wire going to EFI relay loses power

Arsenii

When the power is lost on EFI Relay, is EFI Fuse still powered on both terminals? Every fuse has exposed leads on the top of it, so that you can use a Test Light to check the power. Make sure to use a Test Light in particular, regular multimeter can really trick you sometimes.

I was actually just going to say check the EFI fuse and relay, the symptoms look very much like it. Take the EFI fuse out and inspect it in details, there may be some unexpected surprises lurking around; you should also check for any signs of corrosion or discoloration on the prongs, which can indicate a bad contact. Take the EFI Relay out as well and verify that it is indeed working, easiest way would be to replace it with a neighboring relay, but you can also rent a relay tester tool for free at any car parts store, just for some peace of mind basically..

Now check where the power is being lost - if one terminal of the fuse is powered and the other is not, then it is the issue with the contact around the fuse, could be as simple as a terminal bent out of shape. If the Fuse is still powered on both ends, but power is lost on the Relay, then it is likely a bad connection from the fuse to a relay somewhere in the fuse box. If the power is present on both ends of a Relay and is missing on the ECU, then it is kind of a pickle, since it likely indicates a bad wire from the Relay to the components the hooked up to it.

Hope this helps and best of luck!