any one can help with this problem,very frustrated,my 2000 ram 1500 5.9 check engine light is on with code p0123 tps,i replaced two tps' to no avail,replaced intake gasket with no luck,then read it could be pcm,and had dodge replace that under factory warrantee and picked up from them and still doing the same thing,cel p0123. This happens when you turn the ac on and just totally makes truck run like a pos,stalling, bucking,now dodge wants to keep diagnosing car at $90 an hour with no results,already have 2 hours of diagnostic genuise,getting a little fead up.Anyone with any answers?The cel will go out when you don't have ac on and immediately come on as soon as ac is turned on and then begin running like crap.hhhhhhhelp

 

Hi drew10,

Yes, we did find the problem. The dealership had the truck all day for what I thought to be an obvious fix. I thought that if they replaced the PCM module as done by an earlier posting that would fix the problem.
They said they found water in two of the connectors to the PCM. One of them was connected directly to the PCM, the other was somewhere behind the engine. I'm sorry I don't have a better description than that for the connectors.
They described the problem thus: The water shorted out some pins in the connector(s), which made the PCM think that I wanted the cruise control to kick in at that particular RPM (I don't even have a cruise control.) the PCM translated the RPM change as a conflict in information between the TPS, the MAP, and RPM. The PCM concluded that this information should result in a code P0123, since it thought the TPS signal must be incorrect.
They cleaned out the connector(s) and problem went away. The AC works fine, no codes set, and the annoying RPM "sag" went away.
By the way. When I first called the dealer about checking this out, they too wanted to charge me by the hour. I pointed out to them the information in my Dodge owner's manual which says this would be an emissions related problem, and therefore would be covered by their 7 year - 70,000 mile warrantee. Since I was well below both numbers, they did a whole day's work for ZERO dollars. All it cost me was a day without my truck.
I hope this helps.
Steve

-------Original Message-------

From: drew10 from Dodge Forum
Date: 07/14/06 18:38:15
To: krajesj52@earthlink.net
Subject: tps 0123 code

I read your post and I'm having the same problem with my 2000 Dodge 1500 5.9.Here's the thing though,at first I tried a new tps sensor,to no avail,so then I put another one in and still the same problem,so I thought it could have to due with the intake gasket sucking air causing it to run terrible a common problem with the 5.9's,so I changed that,again no fix still same code.So then I found you're post about the pcm, lucky for me it was still under warranty,so Dodge replaced pcm with brand new one,and guess what it didn't fix the problem,they said it was fixed and the day I went to pick it up I turned on the ac and there it was again check engine light with p0123 code tps sensor,I'm stumped and obviously so is the dealer,now here's my thing the dealer wants to diagnose the problem at an hourly rate and I'm not happy about it at $90 an hour,they are 2 hours into it and haven't shed any light on the problem.My question to you is what was the fix to your truck,any answers would be a greatly appreciated.I haven't found any other related topics but yours on the forum.Thanks again for any help on a very frustrating proble.

 

Hey thanks alot,I'll take my shot at the connectors,and let the dealer know about this they still have the truck.I'll let you know how I make out.Thanks again.Just one last thing did this happen to happen to you after pressure washing the motor.I think I recall this seemed to happen about a day after I cleaned my motor.

 

I purchased the vehicle used last December. The dealership may have cleaned the engine compartment prior to putting it out on the lot. I don't know. It seems to make sense that your cleaning coincided with the problem, though.
I, too, like to work on a clean engine. Be careful in the future about pressure washing. The water can get forced into places hard to find, and worse, hard to dry out.
I used a bug sprayer with a 50/50 solution of Simple Green applied to a WARM engine. Rinse with a low pressure garden hose set to "shower" or equal. Repeat if necessary. Once done properly, it should be easy to keep up later. Rule of thumb is not to spray anywhere you don't want future problems. Sounds simple, but stay away from relays, connectors, etc.

 

krajesj52
One of your previous posts mentioned something about A/C relays. Did this have anything to do with the problem? I replaced my tps and am still getting code 123, but my A/C occasionally doesn't work. I thought the problems were unrelated until I started searching this forum. So, was it just the "bad" connnections or were there some relays that got replaced as well?

Thanks,
Kevin

 

Kevin,
When I swapped the AC relay out, I was trying to narrow down the crummy performance as mentioned earlier. If you note the part numbers on the AC relay, you will also note the similar part numbers on the adjacent relays. There is one I swapped with (don't remember which) that wasn't as necessary as the AC. The problem stayed, so I knew it wasn't the AC relay.
I also wanted to see if there was any kind of problem with the AC compressor maybe causing the problem. By pulling the relay and looking now for the problem, I could determine which direction to go. As noted, the AC compressor didn't matter if it was running or not. The disassembly and cleaning seemed to do the trick.
Steve

 

Thanks Steve.

I unplugged the connectors to the pcm but didn't see any evidence of corrosion. The weatherstripping on the cowl above the pcm was missing, however. I'll keep looking.

 

You have to do more than unplug the PCM connectors. They come apart (carefully).
There is a piece of plastic used inside the connector to lock the pins in place. This piece slides from side to side to lock/unlock the pins from the connector. You'll see what I mean when you get into it that far. I think mine is red in color. This will give you access to the back of the solder pin connections and the weatherproof? gaskets.
IMPORTANT!!! Be VERY careful if you take the connector apart that far not to lose the pin to its mating hole orientation!!! The resulting proble(s) are obvious.
If you have any water/corrosion, clean it out and spray the inside with a water repellant spray of your choice.
My mechanic also said there was another connector to check near the back of the engine by the distributor (sorry, I don't know the number of this connector).