No power to the starter

Tiny
JSTOWE
  • MEMBER
  • 2007 TOYOTA AVALON
  • 3.5L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 250,000 MILES
I replaced a bad alternator and battery. When I got everything back together, the starter would run but the car would not start. I did not seem to be getting fuel or spark, I wasn't sure which. I finally found that I had broken the black wire on the crankshaft position sensor while getting the alternator around the wiring harness. I soldered that wire and put everything back together. Now the starter is not turning over. I have a charged battery. There is no power to the starter. I also found that there is no power to the OBD port. I checked all my fuses, and they are good. I'm not sure what to check next. I will try checking relays next. Does anybody have thoughts on what else I might test or try?
Saturday, February 12th, 2022 AT 12:19 PM

22 Replies

Tiny
KASEKENNY
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There are a number of causes for this, but it sounds like things are getting compounded the further we go.

So, we should take a step back and find where we have power in this circuit and where we don't.

If you don't have power on either wire at the starter then we have something else going on, but I suspect you have no power on the trigger wire from the relay.

If that is the case, then turn the key on and remove the relay to jump the terminals of 3 and 5 and see if the starter turns. If it does then you have a relay issue.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If the starter does not, then we need to check power on pin 1 and 5 and see if there are 12 volts with the key on. Here is a guide that will help with this:

https://www.2carpros.com/articles/how-to-check-wiring

Let's start with this and go from there. Thanks
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Sunday, February 13th, 2022 AT 12:46 PM
Tiny
JSTOWE
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Thank you for the guidance. I checked the relay, and the starter does run when I place a jumper across terminals 3 and 5. I checked voltage between 1 and 2 and am only getting.9 volts when turning the key all the way. Should I be getting 12 volts there? I also checked voltage across 1 and 5 with the key on and got less than 1 volt. Based on that it appears that I am not getting voltage to the relay. I still do not get voltage to the OBD port. Lights do come on the dash, and I can hear the fuel pump running. When the starter was turning over with the jumper, the engine still would not start. Battery voltage was down to 12.2v after testing these things.
Do you have any guidance on the next steps? Thanks in advance.
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Monday, February 14th, 2022 AT 7:14 PM
Tiny
KASEKENNY
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Okay. We need to start tracing these down one at a time because they are most likely related.

You are correct that you are not getting power to the relay on pin 1. So, if you go back to the wiring diagram and follow the wire from pin 1 down to the connector and then to the Park Neutral switch and PCM.

We need to next put the relays and everything back in properly and then jump the PNP switch and try to start the engine.

I am attaching the location, but you should see a two-wire connector and just pull that off and jump the terminals together which will close it to the PCM.

Once we know what this does, we can take the next step because if the engine turns over then this switch is not closing when in park and preventing the PCM from sending voltage on pin 1 of the relay.
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Tuesday, February 15th, 2022 AT 8:46 AM
Tiny
JSTOWE
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Weather slowed me down a bit but thank you for sticking with me on this. My wiring connector to the PNP switch is a 9-pin connector as shown in the picture below. I am having a hard time finding a wiring diagram for this. I assume the two larger pins in the middle are what I need to jump but don't want to short anything else out.
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Thursday, February 17th, 2022 AT 4:52 PM
Tiny
KASEKENNY
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Correct. The PNP is a 9-wire connector but there are only five wires related to this. You need to jump 2 to 6 as this will tell the ECM that it is in Park.

I attached the diagram for just the switch below.
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Friday, February 18th, 2022 AT 10:18 AM
Tiny
JSTOWE
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Okay, I tested this, and I do not get any turning over when I jump 2 to 6.
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Friday, February 18th, 2022 AT 4:29 PM
Tiny
KASEKENNY
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Okay. That helps. One thing I should have clarified is if you have the smart key system or not?

I just looked at the OEM wiring diagram and they show pin 4 and 5 for the PNP switch in the starting system. This is different than the AllData diagrams and I think it is due to the smart key system.

So, let's just try and jump 4 to 5 and crank the engine.

If it still does not crank, then all this does is confirm the park neutral switch is not the issue.

So once we do this we can move on. Clearly the relay being jumped proves out the starter and wiring. So, we need to find out why the ECM is preventing the start.
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Friday, February 18th, 2022 AT 7:33 PM
Tiny
JSTOWE
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I have a regular key (not push start) but it has a chip in it that is detected when it is in the ignition. Connecting terminals 4 and 5 did not cause the starter to turn over.
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Saturday, February 19th, 2022 AT 2:41 PM
Tiny
KASEKENNY
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Okay. So, moving on because the park neutral is not the issue then.

So now let's go to the starter relay and remove the relay and check power. You said previously that when you check power across 1 and 2 that you got less than one volt? If that is the case, then we have a ground issue or the PCM is not supplying 12 volts.

So, let's remove the relay and check power at pin 1 using the battery ground as a known good ground. You should have 12 volts. Do not use pin 2 because we need to do one at a time to see which side is the issue.

Then check pin 2 (ground) by putting your red meter lead on battery positive and then the black lead on pin 2. You should have 12 volts. This proves the ground is good.

Let me know what you have on each one of these and we can determine what is next.

Thanks
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Saturday, February 19th, 2022 AT 4:11 PM
Tiny
JSTOWE
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Testing across 1 and battery ground gives me just a tiny 2 mV. Testing across pin 2 and battery + gives me 12.1 volts.
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Monday, February 21st, 2022 AT 11:37 AM
Tiny
KASEKENNY
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Okay. So, that means the PCM is not commanding the starter on. This is most likely the PCM but let's just double check voltage going to the PCM and if you have voltage coming in but not out and the park neutral is not the issue then your PCM is the issue.

Take a look at the wiring diagram below. I listed out the power flow, but it starts at the ignition switch. Goes through the junction connector down to the PCM. This is the ignition switch input basically telling the PCM that you turned the switch.

Then it sends voltage out of the PCM to the junction connector where it runs through the park neutral switch. If it is closed, then it sends the voltage to pin 1 of the relay with closes the contact (pin 3 and 5 are closed) and the starter turns.

So, if you have no 12 volts on pin 1 we just need to confirm the PCM is getting the signal and not sending the signal. Then replace the PCM.
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Monday, February 21st, 2022 AT 7:03 PM
Tiny
JSTOWE
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Sorry for the slow follow-up. We had a few bad weather days then I was travelling.
I checked the voltage on connector D47 using my voltmeter from pin 2 (red wire) to ground. When the key was turned to start the voltage bounced around between 0 and 1 volt. When I released the key back to the start position the voltage went up to 10 volts. I double-checked the battery voltage, and it was at 12.2 volts.

It seems to me that we should be getting 12 volts when we turn the key to the start position. Earlier in this process, we bypassed the relay and ECM when we placed a jumper between pins 3 and 5 on the starter relay and we got the starter to turn over. That seems to indicate that turning the key to start is sending 12v out pin 8 on the ignition switch but not on pin 1 of the ignition switch.

Looking at the diagram power runs through that ALT fuse (120A) and the AM1 fuse (7.5A). The AM1 fuse was good but I am having a hard time figuring out the ALT fuse. It is part of a fusible link block assembly, and I haven't figured out how to get it out to know if it is good. There appear to be 5 fuses as part of the assembly but only 3 are labeled in the diagram on the cover. The pictures below are really hard to see but may help you see what I am looking at. The block assembly that is easy to see is a picture of the part taken off the internet for comparison. When looking at the picture the ALT fuse is located to the right of the picture. The picture of the fuse locations is rotated 180 degrees.
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Tuesday, March 1st, 2022 AT 6:19 PM
Tiny
KASEKENNY
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That is good info.

Let's just double check when you are jumping 3 to 5 on the relay.

If the starter is turning over when you do that is that when you jump the relay and then turn the key?

If that is the case, can you remove the relay again and check the voltage on pin 1 when you are starting the engine? You should have 12 volts here as well. If not, then the PCM is the issue.

As for the red wire from the ignition switch, that should have 12 volts when cranking the engine. However, if you are jumping the relay and cranking the engine then that is not the issue, and I am just reading this diagram wrong.
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Wednesday, March 2nd, 2022 AT 4:34 PM
Tiny
JSTOWE
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I double-checked. The starter turns over when I jump 3 and 5. The voltage on pin 1 has just under 1 volt when the engine is cranking but goes up to 8 volts when the key is in the on position.
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Wednesday, March 2nd, 2022 AT 7:10 PM
Tiny
KASEKENNY
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Okay. It appears the ignition switch is the issue. I am not sure why they do this, but it is a Toyota thing. They have two switches in the ignition switch which sends 12 volts when you turn the start position.

The red wire that you are only getting 1 volt on when starting the engine appears to be the issue. So, do you have that exposed that you can run a jumper between the blue wire pin 8 to pin 1? Basically, what you are going to do is put 12 volts to that circuit when the blue wire gets 12 volts.

If the starter spins, then this is the issue that you are not getting 12 volts on this circuit.

Take a look at the OEM diagram that I attached below because I think this makes more sense than the other that I was using.

You will see that the red wire feeds the park neutral switch but also the ECM. Jumping the PNP does not work, and I suspect that is because there is no voltage on that circuit.

So, let's do this and then I would replace the ignition switch.
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Thursday, March 3rd, 2022 AT 12:56 PM
Tiny
JSTOWE
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So, I pulled wiring to the ignition switch and found that I wasn't getting voltage to the switch across pins 1 and 2 but was across 7 and 8. I traced back through the wiring diagram and after a battle getting the 120A ALT fusible link block assembly out, I found that it had blown, which explains why we weren't getting any voltage through. This was the fusible link I sent pictures of above but couldn't get a good look at it until I pulled apart the fuse box and extracted it. I have a new one ordered from the dealership. I am hoping I just accidentally shorted something when I reinstalled the alternator and that there isn't still a looming problem that will cause it to short again. I will update you when I get it installed. I really appreciate your time walking me through all of this. I have a much better feel for how to work through electrical issues now.
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Saturday, March 12th, 2022 AT 2:47 PM
Tiny
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Great job and thanks so much for updating us as I am sure that info will help others in the future. Let us know but it sounds like you got it.

Thanks again.
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Sunday, March 13th, 2022 AT 7:37 AM
Tiny
JSTOWE
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Okay. I was hopeful. I made progress but there is still something lurking. I replaced the fusible link block assembly, made sure all of my loose wires were connected again, tried to start it and got nothing. The dash and everything lit up, but the starter didn't even begin to turn over. I pulled the starter relay, jumped pins 3 and 5, turned the key and the car started up. I figured it must be a bad relay. Then I double-checked voltage across pin 2 and the battery + to make sure I had a good ground and got 12.6 volts as expected. When I tested the voltage across pin 1 and the battery ground and turned the key to "on", I got 8.5 volts. When I turn it to crank the engine, it drops to 1 volt. This tells me the circuit is not getting enough voltage to trigger the relay, so it is most likely not the relay.

Is it the computer? Is it a bad ground somewhere? Where else could we be losing voltage? I am also wondering why the 120 amp fusible link block assembly blew in the first place. This issue started after replacing the alternator and battery.

I will go back and check voltage into and out of the ignition switch and retrace my steps from before.
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Wednesday, March 16th, 2022 AT 5:47 PM
Tiny
KASEKENNY
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If you are checking voltage at pin one when cranking the engine and the relay is removed, you should have 12 volts. You will not have 12 volts when you go to the on position because this would trigger the relay to close in the on position and not start.

However, when cranking if you do not have 12 volts then this does sound like the ECM is not sending the 12 volts required or you are losing the voltage somewhere along the way. You do have a junction block and splice between the ECM and relay. So what I would do is ohm out the wiring between the ECM and relay and make sure there is not high resistance.

If not, looks like the ECM is not powering the relay.
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Thursday, March 17th, 2022 AT 4:53 AM
Tiny
JSTOWE
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I went back through the circuit checking voltage and then realized that after I replaced the fusible link block assembly I did not go back and check the 7.5 amp fuse in that same circuit. When I originally checked it at the beginning of all of this it was good, but it looks like it probably blew at the same time as the fusible link. I dropped a new fuse in, and it fired right up and is back on the road.

Thank you again for walking me through this process. It has been a great learning experience.
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Tuesday, March 22nd, 2022 AT 3:07 PM

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