I'm getting diagnostic codes 1537 and 1538 on my 98 4.2. The code is for an intake manifold runner control stuck open. The scanner showed I was getting power to both inrc's, but bank one was not funtioning. I pulled the upper intake and replaced the bank one imrc. All the lines looked good and not coroded so I assumed this was the correct thing to do. After I bolted everything back together I went on a test drive the chek engine light came on again. I have reset the computer 3 times since then and the light keeps coming on and showing the same 2 codes when I scan it. Does anyone have any ideas? This truck runs great, and has no other problems besides this freaking check engine light. PLEASE HELP!

 

Take a look at the vacuum lines on the other end. Behind the battery tray the main vacuum tree branches out to the engine systems. Pull the sheath back from the main junction and start following the vacuum lines from there. Don't be surprised to find they have lots of holes. This happens from the battery acid and gas getting to the vacuum lines.

Take the battery out and look behind where it goes to find the main vacuum harness. The sheathing hides most of it so you will have to learn to recognize it.

Troubleshot the exact problem on mine. It not only solved that problem, it also solved a rough idle I was having.

Good luck,

Tom

 

Thanks for the help, I followed the lines, removed the battery and followed another line, and still found nothing. I borrowed a scanner from a friend and was able to test everything. The imrc's were both working, but bank one was not reading anything. It woulnt say "off" or "on" like bank two did, it just read "no". Any suggestions?

 

Yes it can't be many things at this point. The Valve operates on a vacuum. If you KNOW that it is actuatiing, then the siganl is being lost by probably a broken wire. The connector is a pain to get off but you do need to disconnect it and do a continuity check on that signal wire to its other end. I will get you a pin to pin connection to verify after you do a visual inspection for an obvious broken wire and tell me that there isn't one.

There are 3 wires off each valve. They all need to be verified.

If you know the valve is moving and have verified that, it has to be an electrical open on the signal now.

 

Thanks for the info. That doesn't sound very fun, oh well.

 

I am having the same codes (on the same engine). My engine doesn't appear to be running rough, the only time there is any sort of roughness is at a stop when the truck is in Drive but it doesn't stall out or anything like that, so my gut instinct is telling me that it is an electrical issue. I just got the truck and the CEL was already on so i have no idea what the truck runs like when the IMRC codes are not flagging.

Can i check the voltages at the PCM rather than at the at the sensors themselves(i hear they are hard to get to). Actually let me rephrase that,i know that I can check them at the PCM, but does anyone advise against that doing that??

I'm also wondering if it could vacuum leak? meaning that there is some amount of vacuum, enough to partially close the valve, but not enough to trigger the "IMRC closed" circuit, so the computer thinks the valve is stuck open but the engine runs close to normally.