another gp question for the pros

[isaacucv]

I need a bit of guidance here, as electrical issues are, well you know. Anyway, I have been searching all day and have learned a lot. So, a bit of background, I replaced my glow plugs with ac60g's on Saturday. To this point I had no real issues, but when its cold it was hard to start and I was getting more smoke out of the left side then the other, and winter is coming. After I replaced them I noticed the resistor smoking. Also, the relay is buzzing rather then clicking, like its moving in slow motion. I tested the relay, and I was getting 24.6v at the top post. I then changed the relay and bypassed the resistor. Now I have 12v at the top post, and 8-9v at each gp. The relay clicks when I turn the key on now, but it still doesn't seem to be cycling the glow plugs. What's the next thing to check? What would cause an otherwise functional system to act up after a gp swap? Any help is appreciated, thank you

 

[doghead]

A voltage drop across the relay means your relay is bad. Change it to a new ST85 or GP109, or one of the other part numbers listed in threads here on SS.

 

[isaacucv]

A voltage drop across the relay means your relay is bad. Change it to a new ST85 or GP109, or one of the other part numbers listed in threads here on SS.

Yea, an ST85 is on the list tomorrow, napa is closed here on Sunday. The one I got is supposed to be the right one according to the parts guy. So am I supposed to have 12v at the gps?

 

[doghead]

Did you recently change your relay? If you used a relay that does not have an isolated coil, you may have ruined your card and plugs.

never believe a parts counter kid. It is not a "ford" relay or just any old relay.

 

[isaacucv]

Yes, today. After I had the initial problem. I asked him about the isolated terminals and he said this was the right one. How do you recommend I test the gp's?

 

[doghead]

Test the new relay. test for continuity between the small terminals and the mounting surface(shiney metal frame). if there is continuity, there is your problem. Wrong relay

measure the gps for resistance, they should be 1-3 ohms.

 

[patracy]

Open readings indicate the plug is burnt out as well.

 

[isaacucv]

Excellent info, I will test both tonight after work. On the gp's I test from the blade connector to the block with the wire disconnected, correct?

 

[antennaclimber]

Yes you can test them in the engine as long as you have a good connection to the blade connector and ground.

I test them out of the engine as shown in the attached photo.

It is always important when performing resistance tests and voltage measurements that you have good reliable connections to the items that are being tested.
Karl

 

[isaacucv]

Ok, I did some testing with the meter. I have a wire running from the negative terminal on the rear battery to the the top post of the relay. With the key off I have 12.2V at the top post and nothing at the other 3. With the key on, I have 10v at the top post, and 10v at the bottom post(orange wires). 11v at the pink/black wire. 9v+ at the glow plugs. All the gp's test 1-1.3ohm when removed. The relay (ST 85) seems to be functioning properly. I noticed when the relay opens it sounds as if is happening much slower the when it closes initially. Could it be the gp controller that's bad?