It's been cold at night here lately so I've been plugging in the block heater. This last week it was quite a bit colder (single digits) and the truck has become significantly harder to start. I tested the extension cord (plugged in a drill) and it's fine. What sort of resistance should I look for on the heater? Does it just have a hard time keeping up when it gets that cold or could it have failed? Before, the valve cover would be noticeably warm when the heater was plugged in, now it's not.

I had the same problem with my '91.5. The block heater element burned out. Also check the cord in the engine compartment to make sure it is not rubbed though or loose on the heater.

Should get around 19.2 ohms between the cord prongs.

You should also be able to take a DMM and put it on the continuity setting and test at the prongs for an open circuit.

Really common for the cords to get damaged. Remove the cord and ohm from end to end as well looking for opens. Not often does a element fail...

I think the power cord to the block heater just plugs in where the element is in the freeze plug hole.

my cord melted at the block heater end. I found the melted area after taking the cord off the element. It just unscrews and pull off. Look at the end there. Auto parts stores usually have the cords. Just bring yours in and match it up. That's what I did and the new cord was only about 10 bucks.

I measured 21.5 ohms at the plug. Didn't have time to unscrew the cord and look closer at it. It's not real easy to get at!

Cord bad and the heater is good... :wink:So I would put a small dab of dielectric grease in the socket of the heater to prevent future problems. I'm pretty sure Geno's Garage has the cords for fairly cheap.

  ISX said:

Should get around 19.2 ohms between the cord prongs.

  NWMontanaMan said:

I measured 21.5 ohms at the plug. Didn't have time to unscrew the cord and look closer at it. It's not real easy to get at!

  Mopar1973Man said:

Cord bad and the heater is good... So I would put a small dab of dielectric grease in the socket of the heater to prevent future problems. I'm pretty sure Geno's Garage has the cords for fairly cheap.

A 10% variance constitutes a failed plug/cord? Not arguing, just curious.. I get it that it's $15 for a new cord, and is "cheap insurance", just wondering what justifies +2.2ohm variance in readings for 120VAC as a failure? I is cornfuzed.

I have a question I believe I know the answer but I would like some feed back. When I plug my truck in it pops the GFCI switch in the garage it never did that before. So I am going to look at it tonight but I believe its the chord Any thoughts would be awesome

Pull the cord off and ohm out the cord from end to end and see if you got shorts to ground or neutral.Then ohm the heater itself without the cord so you should see resistance. Someone help me out here its like 20Ω to 30Ω roughly guessin'

Ok so I checked the cord which is the bumper setup from Geno's. Anyways no visible wires looked really good I did check the plug ends all is good. I forgot to check the ohm's at each end of the chord also the heater element I dont know why but I didnt probably will try tomorrow. But I did check the ohm load on the whole system which measured 15 ohm's on the two side by side prongs not the ground. So does that help what could be wrong?

if it's supposed to be 19ohms, and yours (ADawg) is reading 15ohms, that more current draw from the outlet, which could trip the GFI circuit. Mine will trip every once in a great while..

  Rogan said:

if it's supposed to be 19ohms, and yours (ADawg) is reading 15ohms, that more current draw from the outlet, which could trip the GFI circuit. Mine will trip every once in a great while..

Ok so should I try another plug in the garage? I guess they are all protected by a breaker right? I just do not need a short or house fire.

In auto diagnosis, sometimes we'd find it easier to eliminate variables rather than go off of measurements. If you try using a different extension cord and it doesn't trip, you know it was the cord. With the rest of the system, it gets more difficult to substitute, but still possible. You can bypass the bumper plug to rule that out. Maybe use some relatively heavy gauge (so, not speaker wire you happen to have lying around) wire to run from the extension cord to the actual heater to bypass the block heater cable. And so on until you determine the culprit part. Hope that helps.

Ok I tried a different outlet that does not communicate with the GFI and it worked!

I had can't seem to find my cord, where are they located?:sick:Sorry for the question, thanks!

  Dave3500 said:

I had can't seem to find my cord, where are they located? Sorry for the question, thanks!

Dave, the cord is generally located at the right headlight/grill area. you may need to open the hood and look just behind the bumper by the pass. headlight. That's where it generally hangs. As for the engine location, it's on the pass. side of the block, below the oil filter, in that area. Yours could possibly be missing.

That's the area I thought, thanks. Yep, MIA!