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I'm hoping you can help me out here. I've fixed the power aspect of the circuit but I'm having a ground issue now on the load side of the starter relay. I have ~12 volts on terminal 30 of starter relay (constant hot) and ~12 volts on terminal 86 (cranking). I also have a good ground on terminal 87 of the control side of the relay. The issue I'm having is a bad ground at terminal 85 of the starter relay. My wiring diagram only shows that it goes to the PCM. I've tried doing research and the only things I could find would be...
NSS
Crankshaft Position Sensor
Wiring
???
I replaced the NSS and I haven't located the crankshaft position sensor yet but I'm not throwing any codes and the truck runs fine once started. I can ground terminal 85 to the glovebox but I'd like to figure out why the PCM is not allowing the signal to ground.
I also found that it could have something to do with security/anti-theft. I'm probably going to try and removing the NSS and installing the old one to see if it makes a difference. If not, I will reinstall the new one. Other than that I'm not sure what else to do for diagnosing or pinpointing the issue.
A spare key would be nice to check . Dealer may check your key to see if good . They usually charge $150 to get another key . You must provide vin and proof you own it . But pats module could be bad, some mobile mechanics can handle this . You can view security light to see if that may be your problem . If it is then time to get pro help . Take all other stuff off your key ring .
May be a bit "out of the box" but, my friend had an issue with similar symptoms. Turned out to be a linkage issue where the shifter cable connects to the transmission. It was not actually in park or neutral as indicated on the shifter at times and would cause the truck not to start. He replaced the connection piece on the transmission (I have no idea what its called) and it took care of the problem. I'm no expert, this just came to mind when I read your post. Good luck and hope you get it fixed soon!
Thanks for the info redfishtd. I didn't know anything about the security system but from reading that it appears to be functioning normally. The light blinks every 2 seconds and when I turn the key "on" the light illuminates for 3 seconds. I'm not sure about the key though. I guess it's possible that the key is bad but would the truck still run with a bad key? I had a Nissan Titan that would only crank and not start when the key got messed up. I tried uninstalling the NSS and reinstalling but that didn't make a difference either.
Jamieat,
I was thinking that might be the issue and that's why I checked the NSS again. I parked the truck on a flat service, put the truck in park and disconnected the battery, then manually override of the shift lever to put in neutral, rolled the truck to make sure it was in neutral, set parking brake, removed NSS and it was lined up. The mark said it was on neutral and I even tried adjusting it while someone was cranking the truck. I'm thinking my PCM might be fried but I'm at the point where I don't think there is anything else I can or want to do. I'm planning on finding a good mechanic to take the truck to. I appreciate the responses.
Some say PCM rarely goes bad but I'm hearing more and more failures . It requires pro help. I'm told to get the new PCM tied into your vehicle ,either a mobile mechanic or dealer . I haven't helped with that , I just read about it .
I know I would be hesitant to jump a ground on that start relay point with the pcm still attached for fear of damaging that output , I would have cut the wire off to the pcm first .
I was assuming it was the PCM, fuse box, or wiring because I checked everything else. I was leaning towards fuse box but both of these seemed outside my expertise. I finally decided to take it to the dealership because the lady quoted me $99 to "diagnose my truck regardless whether it takes 1 hour or 3 hours". I dropped it off 11:30 a.m. Tuesday morning. She said she would need the truck for about 4 hours and I jokingly said "keep it all week I don't care". The whole day went by and I didn't hear anything. Next morning she calls me and asks if I'm willing to authorize another $99. She told me the technician couldn't figure it out but that he has been working hard and has definitely earned that $99 lol. I said okay that's probably true but I don't want to get another call saying hey we need another $99 because we're stuck. She told me that the technician found out there was no signal coming from the fuse box and he needed to figure out why but he doesn't suspect the PCM. I say alright cool he doesn't suspect the PCM so it's probably the fuse box. She says yeah either the fuse box or the wiring he needs to do more testing to find out.
I authorize the extra $99 Wednesday morning like 8:00-9:00 a.m. because I'm already in this deep and I would like an answer. The whole day goes by and nothing. Thursday morning comes around and she calls me up. The technician finally figured out what was wrong! She told me my PCM was bad. I said "you told me yesterday it wasn't the PCM". She said "I told you that he didn't SUSPECT it was the PCM". Haha... I'm like alright how much is the replacement part? She quoted me over $1,000 for a new PCM!!! That is insane!!! I immediately said no I will bring you guys a part I find. I searched and searched the internet. I found a good deal with a website called protechautosystems. Link: http://www.protechautosystems.com/
The had a replacement PCM that was already flashed and with an extra set of un-cut keys for $500. This was a plug-n-play type deal. I could install the PCM myself and it was supposed to be flashed to my vehicle already. I also found flagshipone and ECM depot during my research. I checked local salvage yards and ultimately found my part on Ebay. Here is the link: http://www.ebay.com/itm/New-OEM-ECM-...FUPcy3&vxp=mtr
This seller is top rated and has great feedback scores. I picked this because the part is only $99.95 and is brand new! I paid for the 1 year warranty which was worth it in my opinion. Anyway if anyone on here is looking for a new PCM/ECM check out this seller on Ebay. It was a great deal! The package arrived a few days later and I took it in to the dealership to have them install and reprogram it for my vehicle. I picked up my truck yesterday and when I looked under the dash the tech had fixed the red/blue wire that I cut but he left the blue/orange wire disconnected. I asked the rep about this but she didn't know and said she would ask him. I know this wire goes to the NSS because I cut it but I'm not sure why he wouldn't fix the connection and just leave it?? I told her that at least the truck works... that's my main concern lol. Anyway I haven't taken the truck for a test drive yet I just drove it home but I'm happy that my truck is finally fixed. Thanks for the help guys!
02-12-2017, 02:34 PM
