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Ask Chad Farhat Your Own Question
Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: Toyota
Satisfied Customers: 3952
Experience:  Owner at Carolina Auto Service & Sales , 20 years Experience in Foreign & Domestic vehicles
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01 Tacoma hit a bump and blew many fuses. Replaced all and

Customer Question

01 Tacoma hit a bump and blew many fuses. Replaced all and now Isolating each component and inspecting wiring and connectors and now blowing ECM Powered fuses. Just got ECM repaired. It had 2? Burned diodes. It still blows the 7.5 amp IGN fuse at the interior fuse panel. I'm a master level technician and so far it is not obvious.
JA: Have you checked the manual yet? Most vehicles have two fuse panels.
Customer: Yes it has also blown the 20 amp underhood EFI fuse. Ive unplugged the igniter module, cruise control, coils, IAC, MAF, and going for oxygen sensors next.
JA: Are you fixing your Tacoma yourself? What have you tried so far?
Customer: Yes Ive also unplugged the transmission relay and HVAC control. The cluster was not blowing any fuses when the ECM was out and it seems to operate. The motor will crank but it blows ECM power fuses. This appears to be a pattern failure on this truck. I am reading the information listed on this page and appreciate the help.
JA: Anything else you want the mechanic to know before I connect you?
Customer: The alternator regulator connector is also unplugged to isolate the "dead short" It was a Clear day when it happed 2 months ago. And when it blew all the fuses, the positive battery terminal seemed to be zapped too. That's all repaired properly now. It is a 2001 v6 manual trans 4x4. 210,000 miles. It cranks but won't fire with no power to the ECM. THANK YOU!
Submitted: 2 months ago.
Category: Toyota
Expert:  Chad Farhat replied 2 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 2 months ago.

Hey how are you

I will try to help you with it

Click on link to view pdf file showing you ECM pin out an wiring power & ground circuit diagram and dlc pin out


when you hit the bump, did you check the under carriage for any wiring harness got smashed against frame and a power wire shorted to the frame?

lets start here

Please let me know if you can view the links

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 2 months ago.




Customer: replied 2 months ago.
Great. I have done a good visual inspection and Yes I can open the links. I will be checkig the circuit continuity and Hoping to find this short tonight. Information is gold. You know this. And by the way I am also Chad. Nice to meet you. The ECM connectors look great. The ecm was sent out and professionally repaired. It had 2 or 3 burned diodes. They gurantee it was ready to be plug and play. Before the ECM repair, The cluster did not blow the fuse when powered up with ECM unplugged. I'm hoping its ok. It lights up warning lights and shows the odometer. So for Help. I am blowing the two fuses still. IGN 7.5 inside the truck and the 20A EFI fuse at the underhood panel. Something is shorting out this ECM I'm about to unplug oxygen sensors or just go for their fuses. I have Alldata at work and printed ecm diagrams and taped them together for a full diagram.
Expert:  Chad Farhat replied 2 months ago.

cool we have 2 chad then .lol,nice meeting u too

do this if you can, are these fuse blowing as soon as you stic new one in there,if you go a litle higher on fuse it will still blow

do you see the evidence of hit ,on the under the frame, inspect that harness from battery down

oxygen sensor wiring smashed against the fire wall or melted around the exhuast manifold

Battery Drainage Test

1- Voltmeter
2- settings on voltmeter will be on milli amps.
3- go across all the fuses in the car and see which one is reading higher than 0.3 to 0.5 milli amps
4- the fuse drawing more than 0.5 miili amps ,will be the suspected circuit that needs inspection for the drainage.

Do you have power on # 16 pin on dlc

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 2 months ago.

This is the starting circuit

check the Transmission position switch at trans

Expert:  Chad Farhat replied 2 months ago.

Fuse list and wiring harness connector location

Customer: replied 2 months ago.
power at pin 16 of the dlc. It is a manual transmission truck. I have unplugged the transmission relay at the right side kick panel. I can plug the ECM in, connect the battery and it blows the two fuses, IGN inside and EFI underhood when the key is turned to the on position. I'll re inspect exhaust and oxygen sensor wiring. It had a Po420 last year, We repaired a minor exhaust leak at the flange near the catalytic and the codes never returned and it passed the smog test. I did not replace any of the sensors. A/F ratio sensor up front I think?
Expert:  Chad Farhat replied 2 months ago.
I want you to probe the power pins on Ecm ,and see which one is drawing high amps ,
Unplug the igntion switch under the steering also , make sure the connector is not melted
Customer: replied 2 months ago.
I couldn't get the A/F sensor unplugged. Ill go to the transmission position.
Expert:  Chad Farhat replied 2 months ago.

why cant you unplug it ,is because it is melted on ,or just hard to get the clip to release ?

Customer: replied 2 months ago.
It's only the fact I cannot get my hand around it. It is located on top of the manual transmission and My lift is a scissor lift in a garage. I might need to lower the trans. My hands vs a very tight location.
Customer: replied 2 months ago.
My diagram for the ecm is for an automatic transmission Tacoma base model. This is a manual transmission model and appears to not have daytime running lights. Exteded Cab by the way.
Customer: replied 2 months ago.
Like I say. It is a Crank no start condition with blowing the two ecm fuses. Connector E5 pins 1 and 2.
Expert:  Chad Farhat replied 2 months ago.

Not sure , I will opt out of this one and let another expert assist you on it

Just do not reply back to me since it will lock question back to me and no other expert can see it to assist you ,just wait and another expert will pick up question for you