is it normal? i have 2 yellow top batteries, when i remote start the truck, it turns on the running lights, (successful start notification) and after the engine starts, and during the glow plugs aftercycling, i see everything dimming excessively, i mean excessively, almost as if the engine is off and i turned the lights on with a dead battery

doesnt seem normal to me, and im concerned cause were now starting to get to the teens and dont want anything going bad on me

once in a while, i get a "glow plug relay controller circuit malfunction" code, but it goes away next time i start the engine, the relay is new

any ideas?

should i run the feed line to the relay straight to the battery using battery cable? or leave it wired as is? wiring is all stock under there

Add ground wires from the body and engine to the grounds on the batts.

Check the volts and amps to the plugs when they are active.

x2 Grounds Ground Grounds....clean them all!

1000X1000 GROUNDS !!! Even if everything seems ok, polish up the grounds! Adding extra grounds is also a good choice.

my lights dim when my GPs cycle

my lights dim when my GPs cycle


Mine also dim. Normal stuff.

i was able to get my hands on a digital VAT-40 inductive coil current tester at school. so i checked the current that the glow plugs pulled and the meter read ~110 Amps. That is quite a load and will cause anything to dim.
My lights dim with the glow plugs cycling as well.

Even with my upgraded crossover and ground cables that are 1-2 gauge cables(thicker than normal 2 gauge cable), my lights still dim and the voltmeter on the dash swings from above 14 normally to 12-13 when the GPs cycle.

i was able to get my hands on a digital VAT-40 inductive coil current tester at school. so i checked the current that the glow plugs pulled and the meter read ~110 Amps. That is quite a load and will cause anything to dim.
My lights dim with the glow plugs cycling as well.

Even with my upgraded crossover and ground cables that are 1-2 gauge cables(thicker than normal 2 gauge cable), my lights still dim and the voltmeter on the dash swings from above 14 normally to 12-13 when the GPs cycle.

I have identical experiences, I think its just a normal 6.5 thing.

Same with me. The GP draws a lot of current, that is why 2 batteries needs to be in top shape. Plus, there is a big current draw from the starter also.

This is all normal. Plugs take alot of current to heat up, especially with eight of em.

ok fellas...

thanks for your input, just wanted to make sure nothing is going to fry,

im going to check and probably run extra ground straps anyway, i have a few laying around

I'm running delco 60 G's each one draws 15 amps for a total of 120 amps. Any glow plug will only short for a very short time, then it will open and fail! The 60G's require a slightly longer on time as each has a built in regulator. on my 93 a manual overide selenoid, dash controlled works well. And yes everything will dim when they are on.I seperated the driver and passenger bank and inserted a 60amp ampmeter in series with each bank, now I know all plugs are working and for how long from the drivers seat. The ampmeters were $10.00 each( JCW) and the 8 gauge wire scrap for free.

Normal operation,

with my dual alternators, I see some dimming.

On one alternator, you can expect voltage to drop below 11 v at idle during glow plug after cycling.

With the dual alternators, at idle, I see a voltage of 13 during the glow plug after cycle.


At idle an alternator might only make 40% to 60% of its rated current.

No worries, keep on truckin'

John