Glow Plug or Controller or Something issue

[7.3IH_Eggrole]

Currently my Dads (1992 F350 IDI) truck is having some WTS light irregularities lately. A couple weeks ago the WTS light was going off within 2 seconds of turning the ignition switch on. For his truck that is normally as sign that the No.7 glow plug is bad. We checked it and the rest with a 12V test light and No.7 was bad. So we replaced all with ZD9's.

The next morning (~20*F air temperature) the WTS light came on and then went off within a couple seconds and the system continued to cycle (click) and he began to crank on it but it was hard to start. After driving to the field he restarted the truck and the WTS light stayed on for ~10 seconds before cycling. It started easy then, but it always does after if first start in the morning.

This irregularity of a short light cycle in cold weather with a cold engine and a longer light cycle with a warm engine in cold air has happened every day since replacing the glow plugs.

I have rechecked the plugs with the test light and they all pass. I see no noticeable breaks or chafes in the the glow plug wires.

Questions: What should I check to remedy this problem and how?

This truck is glow plug dependent and as it gets colder it needs them more.

Thanks

 

[Dave 001]

I have rechecked the plugs with the test light and they all pass.

The test light method just means that there are no opens in the glow plug. It does not mean that there are no shorts in the glow plug. Having said that, they are all brand new and should be good but stranger things have happened.

Check for good grounds.

 

[7.3IH_Eggrole]

So I think I'm going to put a new glow plug controller on this truck for him to see if that cures this problem. I've got some hub issues on my truck (some of you might have seen my other thread going right now) and I might drive his in the mean time.

What is the best controller for this truck? If you can provide a part number too that would be great.

Thanks

 

[icanfixall]

Before spending money on the controller take a look at the main engine wire harness plug. See the two tiny yellow wires at the end of the plug. Those are the feeds to the controller from the battery. That two lines are always electrically hot so be careful around them. Follow the electrical path back from the solenoid. It goes directly to the battery just like the main alternater charge wire does. Be careful working around that one too. Anyway that main harness plug gets corrosion in it and shorts out melting it. Mine did so I ran a direct from the fender mounted solenoid diectly to the controller with 4 gauge speaker multi strand wire found in any sterio shop. No more slow start issues because the controller is getting all the power it needs. Not what it can get thru a tiny plug connecter. When you have the plug apart look at the very tiny pins that has to transfr all the power to the controller... Any crap on them and it heats up melting the plug. Checking with a multi meter will tell you there is power getting to the controller but not enough to make it work as designed.. This is a known problem with these systems. Two small wires are cheaper than one big wire that can handle the load... Look at any high voltage cable hanging from those huge metal towers running acorss country... They have 2 or 3 wires per run because its cheaper doing it that way...

 

[7.3IH_Eggrole]

Before spending money on the controller take a look at the main engine wire harness plug. See the two tiny yellow wires at the end of the plug. Those are the feeds to the controller from the battery. That two lines are always electrically hot so be careful around them. Follow the electrical path back from the solenoid. It goes directly to the battery just like the main alternater charge wire does. Be careful working around that one too. Anyway that main harness plug gets corrosion in it and shorts out melting it. Mine did so I ran a direct from the fender mounted solenoid diectly to the controller with 4 gauge speaker multi strand wire found in any sterio shop. No more slow start issues because the controller is getting all the power it needs. Not what it can get thru a tiny plug connecter. When you have the plug apart look at the very tiny pins that has to transfr all the power to the controller... Any crap on them and it heats up melting the plug. Checking with a multi meter will tell you there is power getting to the controller but not enough to make it work as designed.. This is a known problem with these systems. Two small wires are cheaper than one big wire that can handle the load... Look at any high voltage cable hanging from those huge metal towers running acorss country... They have 2 or 3 wires per run because its cheaper doing it that way...

Alright, I'll try anything once.