Engine/Transmission (1998.5 - 2002) Intake grid heater

[JVackiner]

Hello all, this afternoon I popped the hood to change my IATS and noticed my intake horn above the grid heaters was a light to medium burnt orange color I checked the relays and they seemed to function properly. I checked the cable terminal studs to ground and they read about 2 ohms with or without the ground cable hooked up. Aren't they supposed to read 0? I am assuming the heaters stuck on for some reason at some point in the last week or so. Any ideas why? I have left them unhooked for now after seeing pictures of one that was burn't black. A search returned 8 pages of useful info but am still not sure where to go from here. I don't really want to go without them as I don't think winter is over in Nebraska.

 

[PC12Driver]

If I'm following you correctly, testing between the positive studs and ground is testing the current flow through the heater grid. In that case, there should be some resistance measured since the heater grid is basically a resistor. I'm not sure if 2 ohms is correct, but zero would not be.



If the intake horn is brown, then the most likely culprit would be one or both of the grid heater relays. I had one stick closed last year (thankfully the vibrations from a blip of the throttle shook it loose before things got ugly) and replaced them both for good measure. I opened both of the relays to see how the contacts looked, and after 8 years and 130k miles they were ugly.



I used Stancor Electronic 120-901 relays for replacements. They make the factory ones look like toys, and they're almost a drop in. If you search, you'll find a thread here on the TDR from a few years back with pictures of how to install them.

 

[grimesja]

I had the same issue but mine has soemthing to do with the power from the ECM or something. Finally, I just removed the relays and the grid, but I still have a 380 code.

 

[JVackiner]

Thanks for the reply PC12, I was not sure if faulty relays were the only way for the grids to stick in the on position or if the ECM could have something wrong and kept sending a signal to keep the heaters on. I will check into new relays. I got the "zero reading" out of a Haynes manual. I may have read it wrong, your explanation makes more sense. I will give that another look also.

 

[JVackiner]

grimesja, I'm going to head down and see if I have thrown a code.

 

[fest3er]

Thanks for the reply PC12, I was not sure if faulty relays were the only way for the grids to stick in the on position or if the ECM could have something wrong and kept sending a signal to keep the heaters on. I will check into new relays. I got the "zero reading" out of a Haynes manual. I may have read it wrong, your explanation makes more sense. I will give that another look also.

If the heaters were stuck on, then you have faulty relays. If you ever noticed flickering in the headlights or dash lights as you traversed any road that was glass-smooth, you have faulty relays. The relays DC used (may still use) were really cheap and weak, not designed to last more than a year or so.



See my relay replacement note. The replacement relays are still working like new after all these years.

 

[JVackiner]

Don't have any codes, according to the "mileage window" check anyway. The consensus is bad relays so that is the direction I will go.



Fest3er, thanks for the relay replacement note, it is printed off and in my Dodge repair tricks notebook.

 

[Bill Weber]

JV - If the heater grids are stuck on you should notice a low reading on your volt meter even while driving. My 97 had a similar problem and it turned out to be the temp sensor in the intake manifold.



Bill

 

[JVackiner]

Bill, last week during some cold weather, even though the PU was in the shop and plugged in, it took longer than normal for the voltmeter to come up to 14. But it did come up, maybe that was when they were stuck on. A couple of weeks back, I took out the IATS and cleaned it but decided to replace it anyway. It was when I popped the hood I noticed the discolored intake horn. I kind of freaked a little and forgot about the IATS. I ordered a couple of relays, they are about $19 a piece now. I am going to replace the IATS and both relays just to be safe. After seeing what can happen when they stick on and don't come off, I'm a little spooked. Rather spend a little now than a lot later!

 

[Bill Weber]

JV - I guess I don't know what an IATS is. When I had my problem and the heater stuck on it would keep the voltage down until I disconnected the relays. Dodge 1st replaced the alternator, when It happened again they replaced some computer part, next time they replaced the relays. Got tired of playing with them. Pulled the sensor and stuck it in some hot water & started the engine. Heaters came on. Replaced the sensor ( about $9) - problem solved.



Bill

 

[JVackiner]

Bill, I appologize for that "Intake Air Temperature Sensor". My idea to change that out came from another thread on low fuel mileage. Finding the discolored intake horn directed me to the grid heater relays and have since found out the two may be related. When my volt meter was slow to rise I did not equate that with the grid heater right away. I hate throwing parts at a problem but they are both fairly cheap and from the information I have gathered from this post and a search am comfortable believing they may both have been causing me some problems.

 

[JVackiner]

I may add also that I would wait and see what happens after changing the IAT sensor but if my relays were bad I don't want to risk having them stick again and causing more damage.

 

[emarsh]

I live in the high desert of southern calif. We don't need the grid heaters much so I added a ford EFI starter relay between the drivers side battery and the fusable links going down to the grid heater relays. Of course this means that the grid heaters DO NOT come on until I tell them to. I used a momentary switch added to the turn signal stock to turn the solenoid on. The reason I used the Ford relay is because that it what I had; it also has a diode inside protecting it so it wil not harm the Dodge computer when the EMF of the coil in the solenoid collapses, this causes a spike that the computer does not need!

 

[JVackiner]

emarsh, good idea also, reminds me that a long time ago when the glowplug controller went out in my '90 Ford 7. 3 for the second time, I bypassed it with a toggle switch on the dash. I had complete control of the glow plugs, really helped the old girl on the coldest days!