No tach

Hi all , I signed up as a new member a year ago to ask for some information. Just now getting back to asking My question. My brother has a 2015 4x4 Tacoma 4.0 auto. It has about 58,000 mi. The alternator had over charged the system. Replaced alternator , and battery. truck would not start until dealership replaced ecm ?? box behind glove box. Long story short auto insurance okayed and signed off of it before dealership was done with it.
Everything works on dash cluster except : tach and speedometer , also the 4x4 light blinks like crazy while engine is running. We tried hooking a code reader up to it but it will not connect to truck. Has 12.3 volts and good ground at code reader plug.
Does the new ecm need to be calibrated to the dash cluster??

 

Did they put a used or new PCM in it?

Toyota PCMs in 2nd gens are essentially plug and play aside from doing the immobilizer reset so it will start and run and writing the correct VIN to it so it matches the VIN of the truck.

Do you have a meter?

 

New , about $2100 worth. We're guessing there was no core on it because the dealership left the old one under the seat. We did hook the old one back up and the truck would not start at all. We have a snap-on and fluke multi-meter.

 

You would have to do the immobilizer reset in any case to swap PCMs or the truck will not run so even if the old one is good it wouldn't run without doing the reset.

Can you talk to any modules on the truck?

Unhook the battery and check resistance between pins 6 and 14 of the DLC, it should be 60 ohms.

Also check between 6 and 4 and also between 6 and 16 it should be >100k ohm ideally it should be OL

 

Code reader will not connect to any control units on 2015 Tacoma. Reading tool works on my 2018 escape and on my wife's 2004 mustang. I will relay your message to my brother and have him do your checks. I am 7 hours away in Oklahoma while truck is on our farm in Kansas. So there may be a time delay on getting test results back to you. I'm talking about other things on the farm may need attended to first. We appreciate any help given so, that is why I'm straight up about the late responses.

 

No worries, I hang out on here quite a bit although I often don't have time to get into detailed stuff during the day.

Do you have a scanner that can do all systems?
I'm just wondering because 2nd gens have 2 networks, CAN bus and a single wire K-Line with different modules on each.

From the symptoms I suspect we are dealing with an issue on the CAN bus.

Also does the coolant temperature gauge work?

 

With both battery cables unhooked , he tested at ohms setting [ the upside down horseshoe] . Between 6 & 14 = 61.5 ohms
Between 6&4= 262.2 ohms
Between 6&16= 61.5 to 61.6 ohms
I had him reconnect the battery cables and test voltage for the can high & low pins at #4 to #6 can high = .368 volts
Between #4 to #14 can low =.094 volts
He ran truck in shed with ac on and shed doors open for 5 min. and heat gauge does not move.

 

I have a video of dash cluster while running, but not sure how to get it on here from my cell phone. ??

 

So that confirms we have an issue with the CAN bus, I don't have time to look up everything that is on the Bus at the moment but off the top of my head the PCM, ABS, and Meter (Cluster) are.
We need to unplug things one at a time until the Bus goes back to normal, do note that the terminating resistors are in the PCM and Meter so at least one of those has to be on the Bus for it to work at all.

You have to put it on a video sharing site and post the link here, native video uploads aren't supported. Only pictures and certain other files like PDFs are supported here.

 

When you post see upload file tap it askes select file find picture on phone and tap wait then press thumbnail should post.
Never mind got betten to job.

 

Well rust ! I think had a photo of super white on here and now poof its gone. Thank you for the info that you have shared with me. Dm93 your last post started out clear like English but then it ended sorta foggy to me. Is the can high and can low supposed to add up to 5 volts or is that only with ag equipment?

 

On a normal auto CAN bus CAN low is a 2.5V bias and pulses to 1.5V when data is being sent, CAN high is a 2.5V bias and pulses to 3.5V when data is being sent. On a scope they would mirror each other if that makes sense.

There are two 120 ohm terminating resistors in parallel, one is in the PCM and one in the Meter. Being in parallel they add up to 60 ohms. If they are both missing the Bus won't be able to communicate, with one missing communication may be possible but there will likely be errors.


It looks like we either have a module that is pulling the CAN bus voltage down or a wiring issue.

I was gona look up diagrams earlier but TIS was down so I'll have to check again later.

 

Great to hear that auto c-can wiring is like ag equipment some what. Can high and can low should always add up to 5 volts. Well I guess we will get started with the electrical P.I.T.A. [pain in the a**]. Well my brother for say , I am 7 hours away.

 

I apologize I forgot to grab you the wiring diagrams last night, I got involved in helping some other people and forgot about it.
I'll get them when I get a chance.

 

Here you go.

 

Wow what happened to my reply and thank you I sent via email two days ago. I don't see it on here. Thank you so much for the wiring diagrams. I will share them with my brother in Kansas. He really only gets to work on this project on the weekends. F.t. job and farming after work. He's burning the candle from both ends. When I get an update from him I will let you know of any information. Thanks Again.