PRND321 Lights, Oil Level Light, Temp Gauge

[olopezm]

Here you go; I've uploaded my diagrams. I hope these work for you.

Best regards,

Oscar.

[ktmccrary]

Thanks for the schematics. The color is great; however, after studying the prints there are so many discrepancies that it doesn't seem to match what I have. But thank you so much for the effort. I am sure most of the print is applicable. One of the issues I have is the temperature sensor. Mine has a dual output (3-wire), but your print only shows a 2 wire sensor.

[olopezm]

That's because the third wire is part of the instrument cluster, hence not pictured in the engine performance diagram.

Check posts #10 and 14, I had previously uploaded that diagram.

Best regards,

Oscar.

[ktmccrary]

Thanks, I didn't look as closely at those drawings as I did these last ones. If C2 is the large black rectangular connector in the engine fuse panel then I think we are getting somewhere. It is clearly evident that one of my spliced wires (the BLK/WHT) was removed from the connector, pin and all, and modified with a solid black wire and double spliced and put back in the box. It is not D# but D3 may be in the wrong place.

On your diagram D3 is the green wire for the temperature gauge, which is also not working. If these wires are mixed up in the block, it could lead me to all 3 problems. Thanks so much.... I'm still looking.

Do you have a reference to the 2, 3, and 4 digit numbers on the wires, like the 135 on the DK GRN line M wire?

[ktmccrary]

It seems that the engine compartment fuse block my have come from a junkyard. It has a blue hand painted 4 digit number on the side of it and I have located a certain problem. Using your print I did find continuity between the green wire on the temp sensor and pin B3 on the C1 connector. From there it is suppose to go to D3 on the C2 connector..... IT DOESN'T. But D3 on C2 is Green and it does go to M on the instrument cluster. I ohmed this as well. So, the connection internal to the fuse block is incorrect. I went the other way and D3 on C2 has continuity with numerous wires in C1, but not B3. It connects to all the following in C1.... A1, A2, C1, D1, C3, B4, F5, C5, E6, F10, B10, D11, and D12. When I disconnect one of the instrument cluster connectors the only electrical connection between D3 on C2 and the C1 block is A1 on C1. And that goes to the low coolant sensor which also intermittently comes on. Apparently I'm reading thru lamps with the cluster connected.

I THINK SOMEONE PUT THE WRONG FUSE BLOCK IN THIS CAR WHICH WAS THE BEGINNING OF THE END FOR THIS CAR.

I've been looking for a fuse block for this car on ebay, and there don't seem to be any available for the year with a supercharger. From the auctions there seems to be a distinction between non and supercharged vehicles. There is a upc label with most of the numbers missing on my box, but is there a specific electrical check I can make to distinguish or prove that this is the wrong fuse box? Thanks!

OKAY!!! I am now concluding that I have the WRONG FUSE JUNCTION BLOCK.

Oscar, on the print you sent FIG. 32 near the bottom left there are 3 internal jumpers shown:
1) B3 on C1 to D3 on C2
2) C4 on C1 to D4 on C1
3) A1 on C1 to E3 on C2

Please someone correct me if I am wrong.

On 1 above there is no connection between those two points, but D3 on C2 is the green wire that goes to M on the instrument cluster, AND B3 on C1 is the signal from the temp sensor. Conclusion: THIS IS WHY MY TEMP GAUGE READS MINIMUM ALL THE TIME.

On 2 above...... EASY. It is in the same block and this connection IS THERE.

On 3 above there is no connection between those two points, but both those points do have Yellow/BLK wires. There is an internal connection between A1 on C1 and D3 on C2.

FINAL CONCLUSION: Wrong Fuse Box Installed.

Now where can I find one? Please analyze my data and let me know if you agree with my conclusions. Thanks.

[olopezm]

You're welcome anytime!, I'm glad you are making progress.

Originally Posted by ktmccrary

Do you have a reference to the 2, 3, and 4 digit numbers on the wires, like the 135 on the DK GRN line M wire?

I'm sorry I can't help here, the diagrams have no reference number for those wires, they are divided along pages 2 and 3. The small image I posted before was from page 2 near top right corner, the sensor symbols are on page 3.

Originally Posted by ktmccrary

I THINK SOMEONE PUT THE WRONG FUSE BLOCK IN THIS CAR WHICH WAS THE BEGINNING OF THE END FOR THIS CAR.

That might be the case, or maybe they "re-wired" the fuse box. People likes to make weird things to avoid spending money, but at what cost?. Just as an example the previous owner of my GP got welded the left trailing arm instead of replacing it; 6 years later I find myself driving at 40MPH and suddenly with a wobbling rear left tire, the good thing is that nothing bad happened! I was driving at 60 MPH on the highway under heavy traffic the night before... Thank god!

Originally Posted by ktmccrary

Oscar, on the print you sent FIG. 32 near the bottom left there are 3 internal jumpers shown:
1) B3 on C1 to D3 on C2
2) C4 on C1 to D4 on C1
3) A1 on C1 to E3 on C2

All 3 are correct; you are doing well!

Originally Posted by ktmccrary

On 1 above there is no connection between those two points, but D3 on C2 is the green wire that goes to M on the instrument cluster, AND B3 on C1 is the signal from the temp sensor. Conclusion: THIS IS WHY MY TEMP GAUGE READS MINIMUM ALL THE TIME.

On 2 above...... EASY. It is in the same block and this connection IS THERE.

On 3 above there is no connection between those two points, but both those points do have Yellow/BLK wires. There is an internal connection between A1 on C1 and D3 on C2.

1.- That's correct, you could try using a jumper wire and idle the engine to see if the temperature increases or you can ground the temp sensor and see if the indicator on the cluster goes all the way up after you have installed the jumper wire.

3.- Again you could use a jumper wire and see if something changes, at least it will give you a good indication but with all of your findings you are pretty sure what's the root of your problem.

My manual does not comes with a reference number for the junction block and to be honest I really don't know if there will be any difference between GT and GTP model. Here is a webpage to the most common part supplier I've seen in the forum:

http://www.moradpartscompany.com/

Maybe a more experienced user like Tim, Bob or Rich can comment on the fuse box...

Best regards,

Oscar.

[ktmccrary]

I couldn't find one on ebay, but I found a 97 Series II SC 5 miles from my home in the junkyard. I got it and the top decorative engine cover for $75.

4 POSITIVE FINDINGS BEFORE I INSTALL IT. It's sleeting right now.

1) B3 on C1 does internally connect to D3 on C2
2) A1 on C1 does internally connect to E3 on C2
3) The Blk/Wht wire at D3 on C1 DOES connect to the other neighboring grounds, unlike my present block (Oil Level Switch Grd).
4) Finally, from the pics of the relay panel I sent, no one noticed that mine had no relay 15. There aren't even't connections in the block on my original block for this relay.

I could test it right quick, but not for everything because I have one engine mount off right now. But with just electrical power alone I should be able to test the oil level switch problem and the PRNDL lights. I'll have to get it back together to test the temp gauge but I can definitely see that this problem is fixed from an electrical standpoint because I have traced all the wires.

I will give you an update when there's news. Thank you everyone for your help and especially Oscar.

New-Old Fuse Box.jpg

[olopezm]

It's good to know you found what seems to be the right one.

You can test the temp gauge by grounding the connector, use a jumper wire between the instrument cluster wire and ground to see at least the needle going all the way to the top.

You're welcome anytime. I hope you get everything fixed with that new fuse box.

Best regards,

Oscar.

[ktmccrary]

All the PRND321 indicators work properly now. AND the Oil Level Light does not come on when put in gear. The surprise.... The temp gauge isn't working still.... but for some reason it has system voltage on it while running. It also does NOT self-test like it seemingly did before.

This system voltage is on pin M on the cluster harness that has the green temp gauge wire when the switch is on, but there is only millivolt power there on the connector itself when disconnected from the instrument cluster (my temp signal).

Now I have to figure out what is backfeeding this seemingly from the cluster itself.

BTW, I noticed another significant difference between the fuse panels. My old one has a 30A fuse in Fuse 39. The cover labels this simply as "AIR (30A)". The replacement neither has this fuse, nor are there electrical connectors for it, nor is there any reference to it on the cover. And in researching this, I cannot find this fuse 39 associated with a Grand Prix anywhere on the internet.

[olopezm]

Originally Posted by ktmccrary

All the PRND321 indicators work properly now. AND the Oil Level Light does not come on when put in gear. The surprise.... The temp gauge isn't working still.... but for some reason it has system voltage on it while running. It also does NOT self-test like it seemingly did before.

Good work, 2 out of 3 after the first try is great!. That self-test thing was weird as other users pointed in your oldest thread.

Originally Posted by ktmccrary

This system voltage is on pin M on the cluster harness that has the green temp gauge wire when the switch is on, but there is only millivolt power there on the connector itself when disconnected from the instrument cluster (my temp signal).

Now I have to figure out what is backfeeding this seemingly from the cluster itself.

mV is way too small for that; that's got to be either system noise, bad wiring/connections or a bad ground somewhere(which is unlikely), do you have the same reading at B3 in the junction block?.

Originally Posted by ktmccrary

BTW, I noticed another significant difference between the fuse panels. My old one has a 30A fuse in Fuse 39. The cover labels this simply as "AIR (30A)". The replacement neither has this fuse, nor are there electrical connectors for it, nor is there any reference to it on the cover. And in researching this, I cannot find this fuse 39 associated with a Grand Prix anywhere on the internet.

That's another indicator of a WRONG box installed, I'm sorry I didn't post these images before. That relay #15 is used when there is a supercharger installed like yours. It controls the voltage to the fuel pump so the engine doesn't starves.

Fuse 39 does not exists in your model .

Best regards,

Oscar.

[ktmccrary]

Originally Posted by olopezm

mV is way too small for that; that's got to be either system noise, bad wiring/connections or a bad ground somewhere(which is unlikely), do you have the same reading at B3 in the junction block?.

This is an actual gauge output, not the idiot light. I measured the sensor output at the closest connector between GRN and BLK and got 147mV when it was up to operationg temperature. With only that connector disconnected I get 12v on the other side of the connector between GRN and ground. That same voltage is of course on B3 and on M on the Insturment cluster. When I disconnect that connector on the cluster the 12v goes away from M and from B3.

I cannot find a direct short to wire M on the cluster itself and any other contact on either connector. It seemingly only connects directly to the gauge. With the connectors connected, but not powered up, I cannot find a short to any other point either.

[olopezm]

Is there any chance you got a bad ECT sensor out of the box?

Have you measured resistance at the ECT sensor just to make sure it's good?



Best regards,

Oscar.

[ktmccrary]

Oscar, I thought we had it, but noooooooooooo. I am getting the proper resistance reading between the yellow (PCM) wire and black, but it is infinite between the black and green (the cluster wire). I removed the sensor, checked it against the old sensor and the old one was the same. So I figured the wrong fuse panel may have caused both of them to fry, and I took the new sensor back to the store and got a replacement, and it reads the same way.

The yellow wire iS within the range on your chart. HELP!!! Can we start a new thread on this? The rest of this thread only pertains to someone who may be comtemplating changing their engine bay power center: MAKE SURE YOU HAVE THE RIGHT ONE.

[olopezm]

Easy my friend don't panic! LOL

I don't think it's a good idea to start a new thread since the problem hasn't been solved entirely, other users won't find the answer to the problem here and the forum will get cluttered anyway; if you start a new one it will be the same symptom as here and besides whoever answers on the new thread will answer here too. Don't worry it will be fixed, trust me.

Now back to the problem. you mentioned you've replaced the sensor with a new one, the reading on the PCM side (yellow wire) is OK but the reading on the cluster side (green wire) shows an open circuit:

1.- You might have a problem with the connector itself on the sensor side. Make sure the female pin is tight and free of corrosion/debris, I would use some spark plug grease in order to make sure it makes contact. Another test would be to backprobe the sensor: insert a wire/paper clip at the back of the connector and take the readings there instead of reading at the junction block.

2.- If that fails... you've already checked the green wire for any cracks or chews, right?. If the wire has been stretched it could have been internally damaged but the cover might still look intact. Check continuity/resistance along the green wire from the sensor to the junction box. If it checks OK check continuity from the box to the instrument cluster connector. NOTE: the resistance value should be near 0.


It's more than clear this is not a ground problem since the yellow wire has the correct readings.

Best regards,

Oscar.

[ktmccrary]

Well, can I take back my last post? I jumped then gun because I had only compared the the GRN to BLK, being relatively open, I didn't think this was the solution; however, I ohmed out every possible combination on both the original one I had taken out, and the NEW one I just returned the other new one for. When I compared ALL readings it convinced me to put the new one in and try it.... AND IT WORKS!!!

Thank you so much Oscar for all your help. I wasn't ready to start replacing things I had already done. But the I/C from the 99SE didn't work either, so I took your advice and here we are again. Obviously, the freakin fuse panel I replaced must've ruined both the old sensor and the new sensor.

Now for anyone that cares, here are the readings I got from both a bad and a new Engine Coolant Temperature (ECT) Sensor:

98 GTP 3.8L SC HUD - 3-Pin ECT

Readings taken with sensors in hand at room temperature (70° F)
Meter reads max of 20MΩ , OPEN means > 20MΩ

B=BLACK Y=YELLOW G=GREEN C=SENSOR CASE


------------OLD (Bad)----------NEW
B---Y------ 2.27KΩ ----------- 2.08KΩ
B---G------ 3MΩ (Floating)----- OPEN
B---C------ 3.1MΩ (Floating)--- OPEN
Y---G------ 5.1MΩ------------- OPEN
Y---C------ 5.2MΩ------------- OPEN
G---C------ 88KΩ-------------- 2.34KΩ

the "bad" being that the sensor did not operate the gauge... the PCM input was fine

The GREEN to CASE readings convinced me to try the new one and it works!!!

THANK YOU FORUM!!! I have tons of smaller issues, but this one is for the books. You don't run into the wrong fuse panel on a running vehicle very often.