1993 GMC C3500 SLOW CRANK, HARD TO START

MCAUTODOC

MEMBER
1993 GMC C3500
V8
2WD
AUTOMATIC
441,921 MILES

I drive a 93 GMC 3500 pickup with a food delivery box on it. VIN #1GDKC34F1PJ516187 with a 6.5 diesel turbo. In the past week it has gotten where it is slow to crank and hard to start, first thing in the morning, during the day on the route or when I take it back to the shop in the evening. It initially gave the indication of battery or charging system problems so I load tested both batteries and they tested fine. I then load tested the charging system and all voltage and amperage readings were good. I load tested the starter and it showed good as well. In the past week the "glow plug" light has only intermittently been coming on, not really very much at all. I'm not that familiar with the diesel glow plug system and controls and need some advice regarding how to diagnose the problem.

1 Reply

RACEFAN966

MECHANIC
5,029 POSTS

Ok bare with me here as I only have limited knowledge on diesels ok. But what you are discribing sounds like a glow plug controler problem. Here is the test procedure for is ok. You will need a digital volt meter for this ok.

Here is the wire diagram too.

Let me know if this helps and how it goes. If you need more I will try to help ok. You will probably need to save the pics and magnify them and then print so you can read them better. Thanks