I tested the wrong relay

I have a 2010 4x4 Tacoma with 4 liter V6 and auto transmission.
My a/c quit working a couple of weeks ago, so I was testing things to help eliminate causes. I read one of the tests was to check the relay for the magnetic clutch on the compressor. The relay was good and then I checked the switched side where the prongs mate in the fuse box which I attempted to do an hour later. I put the relay back in because I had to go to the bank and would do it when I got home.
I came home and continued with testing, so I pulled the relay and bridged the switched receptacle in the fuse box and started the engine and turned on the air. I got no compressor movement so I turned off the air and engine. I pulled the wires off and noticed I pulled the wrong relay. I had bridged the A/F Heater instead of the Mag Clutch. I now have the Check Engine and Anti-skid lights on.
I went to O'Reilly and got a readout. These are the codes I have :
P0102 mass or volume air flow sensor "A" circuit low
P0031 heater control circuit low bank 1 sensor 1
P0037 heater control circuit low bank 1 sensor 2
P0051 heater control circuit low bank 2 sensor 1
P0057 heater control circuit low bank 2 sensor 2

I also have additional DTC's in the Anti-lock brake system
C1201 Engine/EV control system malfunction
C1241 Low or High power supply voltage

I hope I didn't ruin the whole computer system, the engine does run in limp mode and the lights wont go out after disconnecting the battery.
I sure could use help in further testing of these codes for what and where to look. I did clean the MAF which didn't help. I tested all the fuses in the box next to the battery. I have a meter and test light. I worked for a dealership in the early 70s when relays were about the most electronics used in cars, how times have changed. I'm not afraid to check and test anything.
Thanks much for any help,
Stan.

 

I'd bet you blew the EFI No2 Fuse (10A).

Why are you trying to jump the MG CLT Relay?
You say you have no compressor operation but do you have a flashing A/C Light or is it on solid? If it's on solid and not flashing it's not a relay/clutch issue, you need to put gauges on it and see if it has refrigerant in it first.

 

DM93, I thank you for answering my post I am grateful you did.
After pulling that fuse and checking it with a multimeter, the fuse was defective. I replaced it and pulled the battery negative cable and both warning lights are cleared. I'd like to buy a code scanner, what's a good one for my 2010 Tacoma and my wife's 2019 Highlander without getting too expensive? $100 or less?
The reason I jumped the relay receptacle, was to see if I could bypass going underneath the truck and checking the mag clutch. I made that mistake and won't listen to that guy again. I did go under the vehicle and found the positive wire and powered the mag clutch with 12 volts and it did lock and unlock when I moved it by hand.
I do have a flashing A/C light and no compressor engagement. I'll go to a shop to have gages put on the system this next week. Are there any numbers he should look for or just see if it's holding some pressure? This was my original problem, now I need the help with it. Should I start a new post for this?
Thank you,
Stan

 

Thank you for circling back!

 

There's so many different scan tools on the market right now it's really hard to make recommendations.
Have a read here and see what you want/need, pick out some candidates and I'll be happy to take a look.
https://www.tacomaworld.com/threads/scan-tool-discussion-recommendations.834898/

Nothing really wrong with jumping a relay but you need to know exactly which pins to jump, jump the wrong ones and bad things can happen as you found out.

Ok so we have a flashing light and the clutch doesn't engage at all, even for a few seconds when it is turned on?

The fact that the light is flashing tells me we have at least enough refrigerant in the system to enable the A/C so we don't need to go that path until we figure out why the clutch isn't turning on.

 

DM93, finally I could get back to you for a report. I had my wife turn on the A/C while I looked at the compressor. The mag clutch does engage for count of 5, then quits and the light flashes.

I'd like to spring for a "all makes/models, all systems scanner" if I could find a reasonably priced one. I'll watch some of those videos when I get back home tonight.

My wife and I enjoy our Toyota vehicles. We've owned 3 so far and this A/C issue and the timing chain in her 4-Runner were our biggest problems. I did have the catalytic converter shields fall off the Tacoma last month. The bolts rusted so I'll put some new ones on and put it back.
Stan

 

So everything is good on the control side, we're most likely dealing with a bad compressor Lock Sensor or an issue with the Lock Sensor circuit.
While the Lock Sensor itself can be removed and tested there's no effective way to check the signal without an oscilloscope.
You can check the Lock Sensor and check circuit integrity but that's about it.

You can probably get into a cabled one without bi-directional controls for $100-$150, on with bi-directional controls will be a bit more (probably in the $150-$300 range). Or if you go with a smartphone based one you can get in at under $100 but do note some have yearly subscriptions although for the capability they have they are relatively inexpensive for what they can do albeit screen size is kind of a limitation when your trying to look at live data.

I love mine, just rolled over 100k. So far the only things I've had to replace on it aside from general wear items are the clutch hydraulics and belt, my only gripe is Toyota's paint is shit. Clear coat on the roof and door sills is starting to go and I even try to keep it out of the sun as much as possible.

 

I'll check out that pickup sensor tomorrow. Is that 2-3 volts the normal amount before using a magnet to reduce it and the other end of the magnet to raise it to the 2-3 volts?

Last month I did have a high fan speed only, I pulled the connector on the blower motor resistor and plugged it back in which corrected that issue. I don't think the resistor is bad just needed better contact.

It's been a long time since I've looked at wiring diagrams, I need to brush up on symbols and meanings.
Stan

 

Pretty sure that's resting voltage, I've never tested one that way. I will say it's a very small signal (only about 300mV) looking at it on a scope.

Probably, not uncommon for it to get a bad connection there and burn up the terminals.

If you have any questions let me know, I know Toyota wiring diagrams pretty well.

 

DM93, thank you for your help. I'm starting to read all those useful threads and information you have at the bottom of your posts. Having worked for a railroad all of my life and only worked in a Chevy garage for a year or so when I was 18, I find it fun to work on my cars again. I like trying to diagnose things and fix them, only I need lots of education with the new cars.
Thank you,
Stan

 

DM93, after watching some videos I like the Kingbolen Ediag Elite. Since I will use this for my own usage on Toyota's and I don't need a lot of speed, plus the price is right. I like it, what do you think of it for someone like me?
Thank you,
Stan

 

I don't personally have one so I can't speak for it but from what I can find on it it looks to be very similar if not nearly identical to the ThinkCar ThinkDiag that I have, it can do nearly everything a $500 tool can just with the limited screen size of your phone.

As with all of the china clones you can expect there to be bugs in both the app and some of the functions may not work but most of the time it's minor stuff, I haven't really found any issues with reading codes and data.

I don't know if it supports AutoAuth or not (mine does not) but it is required to get into 18+ Chrysler/Dodge/Jeep/Ram & 21+ Nissan/Infiniti to do anything other than read codes & data.

If all your doing is Toyota for DIY I don't see why it wouldn't work for you.