Need help with voltage drop...

[MikeO]

... hey guys, long time no speak. I've been busy with work and I think it's been about a year since I last posted after changing out the injectors.



Anyhoo... been having a problem with voltage drop since this summer. Here are the two scenarios.



1. Warm outside temps (summer). Turn key, Wait to Start light comes on (it shouldn't at 100F outside temp) and doesn't go off before starting. I start it after being a good boy and waiting for the light to go out (but it never does)and voltage is still low like the air heater grid is working. Doesn't cycle on and off like it's the heater grid. Wait to Start finally goes off after 15 minutes at which point the voltage returns to normal indicated levels.



2. Cold outside temp (like today). Turn key, Wait to Start light does not come on. Voltage is very low pre-start like the heater grid is draining the system but it starts right up. Indicated voltage stays low for 15 minutes at which point the Wait to Start light starts to flash. While the light is flashing I can hear a relay under the hood somewhere clicking away. Wait to Start light flashing/relay clicking gets faster and faster until it finally comes on and stays on. The whole time, the indicated voltage is still low (<10V). Finally, after about 30 minutes of run/drive time the Wait to Start light goes out and voltage levels go back to normal.



I've tried searching the forum already but I haven't found another post with this same issue. Just looking for some guidance on where to start.



Thanks in advance,

Mike O.

 

[Andy Redmond]

Kinda slammed right now, let me think on this one and try to respond next week.



Do a search for "voltage regulator" on the first gen. forum. . you may likely find some helpful tips. .



It's been a while since I messed with the wait to start light on a first gen. . on the second gen's it comes on no matter the temp as part of the key on sequence. Anyhow the IAT (intake air temp sensor) should not turn the grid heaters (under air intake horn at intake manifold) relays for air intake heater on ds fender (two relays on a bracket), unless the ambient air temp is 50 ish or less.



They are not like glow plugs on some diesels where you wait to start even in warm weather, hit the key and go, unless its 40's or less outside.



If you are comfortable with it, take it to a reputable shop and have them perform a basic electrical analysis on the battery and charging system. If you hear the words voltage drop, on the load and ground sides, you have found a shop that knows how to diagnose the electrical system.



Good luck

Andy