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 I am going to at least begin this mod today. I just received my 150amp breaker yesterday from Amazon, I'll still need to pick up an online fuse holder for the pcm as well.

 I do have a couple of quick questions.

 1. What size fuse for the PCM? I read both 7.5amp and 5amp. 

 2. I read that the ac noise would affect cruise control somehow on a manual truck. I haven't used my cruise much, just wondering how it affects this? Any other things it could mess with?

 I will take ac noise readings before and after to see how this works out and report back when finished. 

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Posted (edited)
1 hour ago, Doubletrouble said:

1. What size fuse for the PCM? I read both 7.5amp and 5amp. 

 

5 amp. Over 100k miles never blown.

 

1 hour ago, Doubletrouble said:

2. I read that the ac noise would affect cruise control somehow on a manual truck. I haven't used my cruise much, just wondering how it affects this? Any other things it could mess with?

 

Anything with a inductive effect sensor. Cam sensor, crank sensor, output speed sensor, ABS sensors. Any inductive sensor creates a AC waveform when AC noise comes from the alternator it confuses any computer. 

Edited by Mopar1973Man
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This show the voltage and amperage on the blue wire from the PCM to the alternator at idle with the headlights on with high beam, the heater fan on high speed, and radio playing; that's a 4.5 amp power draw.  If the load on the alternator load increase there is a chance the 5 amp fuse will blow so I sized mine to 7.5 amp.    

 

 IMG_5844.JPG.d6a692218ab2ae819a51dbdc4af27eda.JPG

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I used a 5 amp fuse and it hasn't blown yet but I do keep a selection of fuses in the truck anyway including 5 amp and 7.5amp

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 I finished the ground mod. Not as bad as I thought it would be other than having big hands in small places. Ran the B+ alt through a 150amp breaker to the pass side battery. 

 Separated all the ground splices in the front of the engine just like in the thread.

 I checked my AC noise before I began (engine still cold, grids not cycling) and had .038-.040. when finished well......see the pic below.

 

IMG_20200501_125127493.jpg

Went for a short drive and the 150amp breaker popped. Not sure why

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Posted (edited)
15 hours ago, Doubletrouble said:

 

8 hours ago, Doubletrouble said:

 I finished the ground mod. Not as bad as I thought it would be other than having big hands in small places. Ran the B+ alt through a 150amp breaker to the pass side battery. 

 Separated all the ground splices in the front of the engine just like in the thread.

 I checked my AC noise before I began (engine still cold, grids not cycling) and had .038-.040. when finished well......see the pic below.

 

IMG_20200501_125127493.jpg

Went for a short drive and the 150amp breaker popped. Not sure why

adings before and after to see how this works out and report back when finished. 

mine went from a .035 to a .010 after the mod on 5 year old AZ alternator.

Edited by dripley
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@DoubletroubleDisconnect the power from the driver's side battery to the grid heater relay then start it up and see if your breaker pops.  You should be able to follow the cable from the battery down to the relays right down by the driver's side battery... at least that's where they are on my 99.

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Unhooked the power cable going to the grid heaters this morning and no problem. Breaker did not pop. Would it be a good idea to clean the terminals on the relays or should I just replace them? 

 Also, it should be fine to leave them unhooked for now since the temps are up?

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mine have been disconnected now for about 9 months all through the winter BUT I will add winters in the UK aren't or shouldn't be that cold in general compared to USA, seen maybe -6C as the coldest this last winter, truck started fine, tucked the cables underneath the battery hold down so If needed it's a quick reconnect and alls good

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I wouldn't mess around, I would just replace them.  I've seen pictures of what happens when they stick closed.  Your truck goes into "meltdown" mode.

 

I think I saw on here that leaving them unhooked will trip a check engine light but if you're ok with that then leave them unhooked.  I think @IBMobile has an article on how to do a switch for them that won't trip the CEL.  That's what I plan on doing to my truck.

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Mine have been disconnected from the battery for 3 or 4 years now. It has not tripped a code yet. Pretty that works for all. If you disconnect the relays them I believe thats how the code gets set.

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2 hours ago, dripley said:

Mine have been disconnected from the battery for 3 or 4 years now. It has not tripped a code yet. Pretty that works for all. If you disconnect the relays them I believe thats how the code gets set.

I'd second that, mine has not set any code relating to the heaters and they are disconnected from the battery

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3 hours ago, dripley said:

Mine have been disconnected from the battery for 3 or 4 years now. It has not tripped a code yet. Pretty that works for all. If you disconnect the relays them I believe thats how the code gets set.

 

1 hour ago, wil440 said:

I'd second that, mine has not set any code relating to the heaters and they are disconnected from the battery

Awesome.  Good to know.  Our current weather here is high 50's to 60's so somewhat cool enough to trigger the grid heaters but not really needed.  Might just disconnect them till winter. :thumb1:

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As long as the relays stay in place, and you just unhook the main power lead, you will not show an error in the PCM.

 

The computer is kinda stupid.  It only checks that there is resistance in the control circuit.  (that is how it knows there are relays there to be cycled.) It does not CONFIRM that power flows from the battery to the grid heaters. 

 

So basically, if you leave the relays in place, the computer thinks everything is kosher.  It doesn't know you have it relaying nothing.....

 

Hag

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Nothing to worry about... Grid heaters for Idaho are only suggested to be used from October to April. After April I typically just unhook the grid heaters its just a waste or power.

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